CAPSULE FILLING MACHINE FOR FILLING TWO-PART CAPSULES AND METHOD FOR FILLING TWO-PART CAPSULES

Description

[0001] The invention relates to a capsule filling machine for filling two-part capsules according to the preamble of claim 1. The invention further relates to a method for filling two-part capsules.

[0002] Capsules are used primarily in the pharmaceutical sector, but also in the field of dietary supplements, to administer measured amounts of a powdery, granular, or liquid preparation. The capsules consist of hard gelatin or similar materials and dissolve after being swallowed, releasing their contents.

[0003] In the case of so-called plug-in capsules, a timed capsule filling machine first feeds in empty capsules, which are positioned upright in capsule holders and then opened. The capsule bottoms are held in a segmented lower section, and the capsule tops in a segmented upper section. After the capsules are separated, the segmented sections swing apart, releasing the capsule bottoms for filling. Subsequently, in one or more dosing stations, the open-topped capsule bottoms are filled with the intended product in a measured quantity. In a closing station, the capsule tops are then placed back onto the filled capsule bottoms. The resulting filled capsules are then removed from their holders in an ejection station and sent for further processing, in particular packaging.

[0004] To ensure compliance with high quality standards, particularly in the pharmaceutical sector, the fill quantity of the capsules is determined and checked for accuracy. Such checks can be carried out on a random sample basis. Often, so-called 100% in-process controls are also in place, meaning the quantity of contents in each individual capsule is determined.

[0005] A well-known method for this is determining the mass of the contents using a capacitive measuring system. During capsule filling, the contents fall through a measuring channel of the capacitive system into the capsule base. An electric field is applied to this channel, and the contents act upon it, causing a change in capacitance. Based on this change in capacitive field, the mass of the contents can be determined during the filling process. This method is characterized by its high measurement speed. Another advantage is that it measures the mass of the contents directly, not the mass of the capsule. Therefore, the described measurement is a so-called net measurement. This means that the measurement result is not influenced by the mass of the capsule.

[0006] Such mass determination using a capacitive measuring system during the filling process is shown in US 2014 / 311 104 A1.

[0007] However, control measurements revealed that the fill quantity can only be determined with limited accuracy. Higher accuracy may be desirable, especially for critical active ingredients.

[0008] The invention is based on the objective of providing a capsule filling machine for filling capsules that enables the determination of the filled quantity of the filling material with high accuracy while maintaining a high production speed.

[0009] This problem is solved by a capsule filling machine having the features of claim 1.

[0010] The invention is based on a further objective of providing a method for filling capsules that enables the determination of the filled quantity of the filling material with high accuracy while maintaining a high production speed.

[0011] This problem is solved by a method having the features of claim 9.

[0012] The invention is based on the understanding that the measured contents, which fall through the measuring channel into the capsule base, are not necessarily completely contained within the closed capsule. The difference between the measured contents and the actual contents of the capsule can be attributed, for example, to the filling or sealing of the capsules. It has been found that, for instance, even the smallest amounts of contents can fall next to the capsule base after exiting the measuring channel. Similarly, when the filled capsule base is inserted into the capsule top to seal them, some contents can spill. To avoid the disadvantages described above, the contents should only be measured after the capsule has been sealed.

[0013] The capsule filling machine according to the invention is used for filling two-part capsules, each consisting of a capsule top and a capsule bottom. The capsule filling machine comprises an insertion station for feeding unfilled capsules into the capsule receptacle of at least one capsule segment. The capsule segment is designed for conveying the capsules. The capsule segment comprises a segment bottom for receiving the capsule bottom and a segment top for receiving the capsule top. The capsule filling machine includes a dosing station for filling a capsule bottom with the filler material and a closing station for closing the filled capsule bottom and the capsule top. Furthermore, the capsule filling machine includes a measuring device, wherein the measuring device comprises a capacitive measuring system. The measuring device is located downstream of the closing station. The capacitive measuring system comprises a measuring section.The mass of the filled, sealed capsule can be measured along the measuring section using the capacitive measuring system. The measuring device includes a guide for the sealed capsule. The guide is designed to transport the filled, sealed capsule from the capsule segment to the measuring section of the capacitive measuring system.

[0014] Accordingly, to fill two-part capsules, an empty capsule is fed into a capsule holder of at least one capsule segment. The empty capsule is fed into the machine at an insertion station. The capsule top and bottom are then separated. The top and bottom are sealed in a closing station. The filled capsule is then conveyed by a guide to a measuring section of a capacitive measuring system. There, the mass of the filled capsule is measured by the capacitive measuring system.

[0015] The capsules are typically fed into the capsule filling machine in a pre-sealed state. In this so-called pre-sealing stage, the capsule base is only slightly inserted into the capsule top, allowing the capsule halves to be easily separated at the separating station. Once the capsule base is filled, the capsule halves are usually completely sealed by a locking mechanism. According to the invention, a capsule is considered sealed when the capsule base and top overlap, preventing the contents from escaping. Therefore, a closed state of the capsule encompasses both a pre-sealed and a fully sealed state.

[0016] This design of the capsule filling machine measures the mass of the capsule when filled with product and closed. Therefore, the gross mass of the capsule is measured. To determine the net mass of the capsule, i.e., the mass of the product, the tare mass of the capsule must be subtracted from the gross mass. The tare mass of the capsule is usually specified by the capsule manufacturer. Since the total mass is measured only after the capsule is sealed, discrepancies between the mass of the measured product and the mass of the sealed product are eliminated. This ensures a high degree of accuracy in determining the mass of the product inside the capsule.

[0017] Preferably, a further capacitive measuring system is provided for measuring the mass of unfilled capsules. The mass of the unfilled capsule can be measured using this additional capacitive measuring system. Therefore, the additional capacitive measuring system must be located at least upstream of the dosing station. Advantageously, the mass of the unfilled capsule is measured before the capsule top and bottom are separated. In a preferred embodiment, the additional capacitive measuring system is located upstream of the insertion station. Accordingly, the mass of the unfilled capsule is measured using the additional capacitive measuring system before the capsule is first inserted into the capsule segment. Preferably, the mass of the contents is determined from the difference between the measured mass of the filled capsule and the measured mass of the unfilled capsule by means of a control system of the capsule filling machine. This is a so-called gross tare measurement.Both the gross mass and the tare mass of the capsule are measured. The net mass is calculated as the difference between the gross and tare masses. The actual tare mass of the capsule may deviate from the manufacturer's specifications. Such deviations, particularly when filling small quantities of critical pharmaceutical substances, lead to undesirable inaccuracies in determining the net mass of a capsule. By measuring the empty capsule, its mass is precisely determined, independent of the manufacturer's specifications. This gross-tare measurement allows for the precise determination of the capsule's net mass.

[0018] It is advantageous for the capsule filling machine to have multiple processing lanes, with the capacitive measuring system comprising a separate measuring section for each lane. This allows for lane-specific measurement of the capsule mass. Lane-specific measurement provides insights into the previous processing of the capsule on the corresponding lane. If a mass of the filling material deviating from the target mass is detected on a processing lane, the individual stations along that lane can be checked for accuracy without having to inspect all stations on other processing lanes. This allows for significantly faster identification of the causes of errors in the process chain.

[0019] Preferably, the guide device includes a lifting unit, which is designed to lift the filled capsule from the capsule segment and position it within the measuring section of the capacitive measuring system. This design of the guide device allows the measuring device to form a module that can be flexibly positioned within the capsule filling machine. For example, the guide device can be arranged at one of the processing stations following the closing station. Preferably, the measuring device is located between the closing station and the ejection station. The lifting unit transports the capsule into the measuring section, where the capsule is preferably held. The capsule is preferably measured statically, meaning that the capsule does not move, or at least hardly moves, during the measurement by the capacitive measuring system.Static measurement allows for very good measurement results with high measurement accuracy.

[0020] In an alternative embodiment of the guide device, the guide device has a guide track that leads into the measuring section of the capacitive measuring system. As the capsule slides along the guide track through the measuring section, the mass of the filled capsule is measured. Thus, the measurement is dynamic. Changes in the speed and position of the capsule during measurement significantly affect the measurement accuracy. Therefore, the challenge of dynamic measurements lies in maintaining a constant capsule speed and a constant distance between the capsule and the capacitive sensor. For this purpose, the measuring section is preferably oriented at an angle to the direction of gravity. The capsule, subjected to gravity, rests on the measuring section and slides down it.Due to the inclined position of the measuring section, the capsule is guided along the measuring section and thus maintains a nearly constant distance to the capacitive sensor of the measuring system. The capsule's speed during measurement can also be kept nearly constant by the inclined position of the measuring section. This allows for high measurement accuracy in the measurement of the capsule mass and, at the same time, a high capsule ejection rate. Such a measuring device is preferably arranged downstream of the ejection station.

[0021] An embodiment of the invention is described in more detail below with reference to the drawing. The drawing shows: Fig. 1 in a top view of a capsule filling machine in a design according to the invention with measuring device, Fig. 2 in a schematic side view of the measuring device, the guide device and a capsule segment, and Fig. 3 in a schematic side view of an alternative embodiment of the guide device.

[0022] Fig. 1 Figure 1 shows a top view of an embodiment of a capsule filling machine 1 according to the invention for filling capsules 40 with a filling material 43 (see also Figure 1). Figuren 2 and 3 The filling material 43 can be provided in the form of a powder, granules, tablets, liquids, or the like. It can be a pharmaceutical preparation, a food supplement, or the like. The capsules 40 consist of a capsule base 41 and a capsule top 42 attached to it, both of which are made, for example, of hard gelatin.

[0023] The capsule filling machine 1 after Fig. 1 The capsule filling machine 1 comprises a rotary table 2 and a schematically represented main drive unit 4, wherein the rotary table 2 can be driven by the main drive unit 4 to rotate about a vertical axis of rotation 3 in timed steps in the direction of rotation 9. The main drive unit 4 comprises at least one electric motor which is operatively connected to and drives the rotary table 2. Preferably, the capsule filling machine 1 comprises a control unit 30 which is coupled to the main drive unit. The control unit 30 is also in Fig. 1 The diagram is shown schematically in dashed lines. A number of capsule segments 5 are arranged at uniform angular intervals on a circumferential area of ​​the rotary table 2. In the illustrated embodiment, a total of twelve capsule segments 5 are provided. A different number of capsule segments 5 may also be advantageous. Each capsule segment 5 consists of a lower segment part 6, preferably fixed to the circumferential area of ​​the rotary table 2, and an upper segment part 7 that is pivotable relative to it. Several stationary machining stations 11 to 22, which do not rotate with the rotary table 2, are positioned around the rotary table 2. Fig. 1 not shown in detail. The number of processing stations 11 to 22 preferably corresponds to the number of capsule segments 5, so that in each rotary position of the rotary table 2, which is clocked in angular increments, each capsule segment 5 is within the reach of one of the processing stations 11 to 22.

[0024] In a preferred embodiment, the capsule segments 5 contain several capsule receptacles 8 for receiving the capsules. In a preferred embodiment, each capsule segment 5 contains five capsule receptacles 8. It may also be advantageous to provide several capsule receptacles 8, in particular ten, preferably twelve capsule receptacles 8. In a preferred embodiment, the capsule receptacles 5 are arranged in a linear, straight row. With a large number of capsule receptacles 5, they can also be arranged in two or more such rows.

[0025] The preferred embodiment of the capsule filling machine 1 comprises an insertion station 11 in which empty capsules, initially provisionally assembled and consisting of a capsule base 41 and a capsule top 42, are inserted into the capsule receptacles 8 of the capsule segment 5. During normal operation, the attached capsule top 42 separates from the capsule base 41. The next processing station is a rejection station 12. Defective, unseparated empty capsules are rejected in the rejection station 12.

[0026] After the discharge station 12, the upper segment 7, with the capsule tops 42 held within it, is pivoted relative to the lower segment 6, with the capsule bottoms 41 held within it. The lower segment 6 is guided to the three dosing stations 13, 14, and 15 following the discharge station 12. In the dosing stations 13, 14, and 15, the capsule bottoms held in the lower segments 6 are filled with the intended fill material 43. It may also be sufficient to provide only one or two dosing stations.

[0027] After passing through the last dosing station 15, the upper segment 7 is pivoted back into alignment with the lower segment 6 via stations 16, 17, and 18. In the closing station 18, the capsules 40 are preferably closed by sliding the previously removed or separated capsule tops 42 back onto the filled capsule bottoms 41. Preferably, the capsule halves 41 and 42 are locked together. Several inspection stations 19 and 20 follow the closing station 18. In the inspection stations 19 and 20, capsules 40 are inspected and, if necessary, rejected. In a subsequent ejection station 21, the remaining capsules 8 that have been found to be acceptable are ejected by means of plungers or other ejection devices (not shown). Further inspections of the capsules 8 can also be carried out in the ejection station 21.

[0028] As in Fig. 1 As shown, the capsule filling machine 1 includes a measuring device 22. The measuring device 22 is shown schematically as a quadrilateral with only dashed lines. The measuring device 22 serves to measure the mass of a capsule 40. The measuring device 22 is located downstream of the closing station 18. As shown in Fig. 1 As indicated, the measuring device 22 can be arranged process-wise between the closing station 18 and after the ejection station 21. Accordingly, only closed capsules 40 are measured in the measuring device 22. Of course, it can also be advantageous to provide several measuring devices 22 in a capsule filling machine 1. At this point, it should be noted that the terms "upstream" and "downstream" are to be understood process-wise in relation to the handling of the capsules 40. Thus, if a first device is upstream of the second device, the capsules 40 in the capsule filling machine 1 first pass through the first device and then through the second device.

[0029] As in the Figuren 2 and 3As shown, the measuring device 22 comprises a capacitive measuring system 23 and a guide device 26. The capacitive measuring system 23 comprises at least one measuring section 25. Furthermore, the capacitive measuring system 23 comprises a capacitive sensor 24 arranged on the measuring section 25. The capacitive sensor 24 generates an electric field that extends at least partially over the measuring section 25. When a capsule 40 is guided into the measuring section 25, it causes a change in the electric field, whereby the mass of the capsule 40 is calculated. As shown in Fig. 2 As shown, in a particularly preferred embodiment of the capsule filling machine 1, the capacitive measuring system 23 includes a reference measuring section 25' to determine the dielectric constant of the surroundings. This allows for an even more precise determination of the mass of the capsule 40 within the measuring section.

[0030] The guide device 26 of the measuring device 22 is designed to transport the capsule 40 from the capsule segment 5 to the measuring section 25 of the capacitive measuring system 23. Fig. 2 Figure 1 shows an embodiment of the measuring device 22, in which the guide device 26 has a lifting unit 27. The lifting unit 27 comprises a lower slide 32 associated with the lower segment part 6 and an upper slide 33 associated with the upper segment part 7. After the capsule upper part 42 and capsule lower part 41 are closed, the entire filled capsule 40 is lifted from the capsule segment 5 by the lower slide 32 and pushed into the measuring section 25 of the capacitive measuring system 23. The measuring section 25 is designed as a measuring channel 34, wherein the measuring channel 34 has a channel opening 35 at its end facing the capsule segment 5. The capsule 40 can be inserted into the measuring channel 34 through the channel opening 35. The measuring channel 34 and the capsule receptacle 8 are approximately coaxial with each other during the transfer of the capsule 40 by the lifting unit 27. The lifting unit 27 can also be part of the locking station 18 in a preferred embodiment.

[0031] Once the capsule 40 is positioned in the measuring section 25, it is preferably secured by the lower slide 32 and / or the upper slide 33. The mass of the closed and filled capsule 40 is measured in the measuring channel 34 using the capacitive measuring system 23. After the measurement process is complete, the capsule 40 is placed back into the capsule holder 8 of the capsule segment 5 by means of the lifting unit 27. Because not only the filling material 43 is measured as it is being filled into the capsule 40, but the entire capsule 40 with the filling material 43 in its closed state, the capacitive measuring process is independent of the filling material 43. Therefore, liquid filling material or similar substances can also be measured. The capsule 40 can then proceed to the subsequent processing stations.

[0032] In an alternative embodiment of the capsule filling machine 1, the lifting unit 27 can, instead of the slides 32, 33, also have other means for lifting the capsule 40 from the capsule segment 5 and / or for holding the capsule 40 in the measuring section 25. Such means can, for example, be compressed air, vacuum, or other mechanical elements.

[0033] An alternative design of the measuring device 22 is in Fig. 3 The guide device 26 also includes a lifting unit 27. The lifting unit preferably includes a slide for lifting the capsule 40 onto the capsule segment 5. It may also be advantageous to provide another means for lifting the capsule 40. Furthermore, the guide device 26 includes a pivot arm 36 with a capsule holder 38. The guide device 26 also includes a guide track 28, wherein preferably a section of the guide track 28 is designed as a measuring section 25. The capsule 40 is lifted from the capsule segment 5 by the lifting unit 27 and pushed into the capsule holder 38 of the pivot arm 36. Once the capsule 40 is in the capsule holder 38, it is held in place by retaining means (not shown in detail). Such a retaining means could, for example, be a vacuum applied to the capsule holder 38. Subsequently, the pivot arm 36 pivots in a pivot direction 37 towards the guide track 28.If the capsule holder 38 is approximately coaxial with the guide track 26, the capsule 40 is released and slides onto the guide track 26 under the influence of gravity. In this case, the guide track 26 is designed as a guide channel. However, it may also be advantageous to design the guide track 26 as an open channel, for example, a trough. The capsule 40 slides down the guide track 26 and passes through the measuring section 25. The capacitive sensor 24 of the capacitive measuring system 23, which generates the electric field, is located at the measuring section 25. The capsule 40 passes through the electric field of the capacitive measuring system 23. The mass of the filled capsule 40 is measured. The measurement takes place while the capsule 40 slides through the measuring section 25; therefore, a dynamic measurement is performed.

[0034] As in Fig. 3 As shown, the guide track 28 is inclined to the direction of gravity G. The guide track 28, in particular its longitudinal axis, forms an angle α with the direction of gravity G, with the angle α being in a range of 5° to 50°, particularly from 25° to 45°. The angle α is preferably approximately 40°. Compared to a drop chute, this results in two significant advantages that allow for increased measurement accuracy. Firstly, the speed at which the capsule 40 traverses the measuring section 25 is reduced and approximately constant. Secondly, the capsule 40 rests permanently against the guide track 28 and thus has a fixed trajectory. Therefore, the capsule 40 always traverses the measuring section 25 at approximately the same speed and in the same position. As already mentioned at the beginning, this increases the measurement accuracy.

[0035] The design of the measuring device 22 with a guide device 26 according to Figur 3 is preferably provided after the ejection station 21. Thus, the guide device 26 can even be part of the ejection device 26.

[0036] The capsule filling machine 1 comprises several processing lanes 44 along which several capsules 40 can be filled. As already explained above, in the present embodiment of the capsule filling machine 1 according to Fig. 1 Five capsule holders 8, and thus also five processing lanes 44, are provided. A measuring section 25 of the capacitive measuring system 22 is preferably provided for each processing lane 44, so that a lane-related measurement of the mass of the capsules 40 can also be carried out. If a mass of the filling material 43 deviating from the target mass is determined on a processing lane 44, the individual stations along this processing lane 44 can be checked for accuracy without having to check all stations of other processing lanes 44. In the measuring device 22 according to Fig. 3 It may also be advantageous, if the measuring section is located downstream of the ejection station 21 or is at least part of the ejection station 21, to provide only one measuring section 25. The capsules 40 are preferably guided sequentially onto the guide track 28, with the sequence of the capsules 40 of the various processing paths 44 being recorded by the control system 30. This allows the measured values ​​of the capacitive measuring system 23 to be assigned to each capsule 40 of the corresponding processing path 44.

[0037] To determine the net mass of the filled capsule 40, i.e., the mass of the contents 43, the tare mass of the capsule 40 must be subtracted from the measured gross mass of the capsule 40. The tare mass of the capsules 40 is known and stored in the control system 30. However, the known tare mass of the empty capsules represents only a statistical average, which is either determined by the user over a specific number of capsules 40 or specified by the manufacturer of the empty capsules. Therefore, deviations can exist between the actual mass of an empty capsule and the statistical average mass of the empty capsule. These deviations can have a significant impact on the total mass of a filled capsule 40, especially when filling very small quantities of contents 43. Therefore, in a particularly preferred embodiment, the capsule filling machine 1 includes an additional capacitive measuring system 31, which serves to measure the mass of the empty capsules 40.The additional capacitive measuring system 31 is an integral part of the capsule filling machine 1. The additional capacitive measuring system 31 is preferably arranged upstream of the insertion station 11 of the capsule filling machine 1, as shown in . Fig. 1schematically indicated by a dashed rectangle. Alternatively, the additional capacitive measuring system 31 can also be part of the insertion station 31. Technically, the additional capacitive measuring system 31 is constructed analogously to the capacitive measuring system 23. Even before the empty capsule 40 is separated into capsule lower part 6 and capsule upper part 7, it is inserted into the measuring section and its mass is measured there. The measurement result is stored in the controller 30. After the same capsule 40 has been filled and its gross mass measured, the net mass is determined via the controller 30. For this purpose, the previously measured tare mass of the capsule 40 is subtracted from the gross mass. The measurement result thus exhibits extremely high accuracy, which means that even the masses of very small quantities of contents can be determined with the highest precision.

Claims

1. Capsule filling machine for filling two-piece capsules that each comprise a capsule upper part and a capsule lower part, comprising an insertion station (11) for delivering unfilled capsules (40) into the capsule receivers (8) of at least one capsule segment (5), the capsule segment (5) being designed to convey the capsules (40), the capsule segment (5) comprising a segment lower part (6) for receiving the capsule lower part (41), and a segment upper part (7) for receiving the capsule upper part (42), and a dosing station (13, 14, 15) for filling a capsule lower part (41) with fill product (43), a closing station (18) for closing the filled capsule lower part (41) and the capsule upper part (42), and a measuring device (22), the measuring device (22) comprising a capacitive measuring system (23), characterized in that the measuring device (22) is downstream of the closing station (18), in that the capacitive measuring system (23) comprises a measuring section (25), along which the mass of the filled, closed capsule (40) can be measured by means of the capacitive measuring system (23), and the capacitive measuring system (23) comprising a capacitive sensor (24) arranged at the measuring section (25), and in that the measuring device (22) comprises a guide device (26) for the closed capsule (40), the guide device (26) being designed to convey the filled, closed capsule (40) from the capsule segment (5) to the measuring section (25) of the capacitive measuring system (23), and in that the capsule filling machine (1) has a plurality of processing tracks (44), the capacitive measuring system (23) comprising a separate measuring section (25) for each processing track (44).

2. Capsule filling machine according to Claim 1, characterized in that a further capacitive measuring system (31) is provided, for measuring the mass of unfilled capsules (40).

3. Capsule filling machine according to Claim 2, characterized in that the further capacitive measuring system (31) is upstream of the insertion station (11).

4. Capsule filling machine according to one of Claims 1 to 3, characterized in that the guide device (26) has a lifting unit (27), the lifting unit (27) being designed to lift the filled capsule (40) out of the capsule segment (5) and to position the filled capsule (40) in the measuring section (25) of the capacitive measuring system (23).

5. Capsule filling machine according to Claim 4, characterized in that the measuring equipment (22) is arranged between the closing station (18) and the ejection station (21).

6. Capsule filling machine according to one of Claims 1 to 4, characterized in that the guide device (26) has a guideway (28), the guideway (28) leading into the measuring section (25) of the capacitive measuring system (23).

7. Capsule filling machine according to Claim 6, characterized in that the measuring section (25) is inclined with respect to the direction of gravity (G).

8. Capsule filling machine according to Claim 6 or 7, characterized in that the measuring device (22) is arranged downstream of the ejection station (21).

9. Method for filling two-piece capsules that each comprise a capsule upper part and a capsule lower part, by means of a capsule filling machine (1), the capsule filling machine (1) having a plurality of processing tracks (44), a capacitive measuring system (23) comprising a separate measuring section (25) for each processing track (44), and the capacitive measuring system (23) comprising a capacitive sensor (24) arranged at the measuring section (25), comprising the following steps: - An unfilled capsule (40) is delivered, at an insertion station (11) of the capsule filling machine (1), to a capsule receiver (8) of at least one capsule segment (5), - the capsule upper part (7) and the capsule lower part (6) are separated from each other, - in a dosing station (13, 14, 15) the capsule lower part (6) is filled with fill product (43), - the filled capsule lower part (6) and the capsule upper part (7) are closed in a closing station (18), - the filled capsule (40) is conveyed by means of a guide device (26) to a measuring section (25) of the capacitive measuring system (23), - the mass of the filled capsule (40) is measured in the measuring section (25) by means of the capacitive measuring system (23).

10. Method according to Claim 9, characterized in that the mass of the unfilled capsule (40) is measured by means of a further capacitive measuring system (31).

11. Method according to Claim 10, characterized in that the mass of the fill product (43) is determined, by means of a control system (30) of the capsule filling machine (1), from the difference of the measured mass of the filled capsule (40) and the measured mass of the unfilled capsule (40).