EP2740671B1 - Device for inspecting tablets - Google Patents

Description

The present invention relates to a device for checking small pharmaceutical products such as tablets or capsules.

An important function when filling tablets or capsules into bottles or other containers is the counting and excretion of defective tablets or capsules. On-the-market systems use different technologies.

Color cameras can detect incorrectly colored or broken tablets or capsules with appropriate image analysis. For this purpose, however, a highly complex evaluation software is required due to the continuous movement of the passing tablets or capsules. In addition, a high illumination cost is necessary to achieve sufficiently sharp image content.

Capacitive sensors can be used to contactlessly calculate the mass of the tablets or capsules passed by and to draw conclusions about the integrity of the tablets or capsules. Such capacitive sensors may also be integrated into a product chute, such as for example US 2009/0090659 A1 is known. However, capacitive sensors are sensitive to vibrations, electrical noise and the moisture content of the tablets or capsules, as well as positional deviations of the products when passing through the sensor area.

The present invention has for its object to provide a device for checking tablets, which is very robust, simple and can be applied to different product types and formats.

This object is solved by the features of claim 1.

According to the invention, the device for checking tablets comprises a product chute having a product guide surface inclined at an angle to the horizontal and a sensor integrated in the product chute for detecting defective tablets during their passage through the product chute. In this case, the product chute on at least a first, stationary product guide portion and a separated, movably mounted second product guide portion, which in series together define the product guide surface. In addition, the sensor has a passive piezoelectric bending transducer, which is connected to the second product guide section, wherein the passive piezoelectric bending transducer is connected to a measuring device which measures at least one voltage pulse generated by the passive piezoelectric bending transducer in bending the passive piezoelectric bending transducer.

With this arrangement, isolated tablets or capsules can be quickly and safely examined for their integrity. The device is extremely robust against external influences and allows use in various tablet shapes and sizes. In addition, the dust generated by tablets by abrasion tablet dust can not distort the measurement result.

Preferably, the guide surface portion of the second product guide portion has the same shape as the guide surface portion of the first product guide portion. In this way it is ensured that the movement of the tablets is not affected during the transition from the first to the second product guide section.

Particularly suitable here is a U-shape or V-shape of the guide surface sections, whereby a stable central position of the tablets is ensured when passing through the product chute and thus also during the measurement.

In a preferred embodiment, the passive piezoelectric bending transducer is plate-shaped and arranged substantially at the same angle to the horizontal as the product guide surface. Thus, even slight weight loads of the second product guide section can lead to the desired deflection of the bending transducer and thus to a measurable signal.

The conditions for a high reactivity of the piezoelectric bending transducer are optimized when the bending transducer is connected in the region of its front end portion with the second product guide portion and is immovably mounted in the region of its rear end portion.

In one embodiment, the first stationary product guide portion of the product chute is connected to a stationary support frame of the product chute and the passive one Piezoelectric bending transducer is clamped in the region of its rear end portion in a support foot provided in addition to the support frame. In this way, a structurally simple integration of the sensor in the product chute is possible.

Preferably, the support leg on two side cheeks defining a gap between them, wherein the side cheeks have on the mutually facing inner surfaces at least one recess for receiving a side surface of the passive piezoelectric bending transducer. The at least one recess has, in a rear end region, an essentially V-shaped clamping surface which is open towards the intermediate space. With this configuration, a secure clamping of the bending transducer between the side cheeks is ensured in a rear end region of the recesses, while at the same time a bending of the bending transducer in the front regions of the recesses is made possible.

For decoupling of external influences, the support foot is preferably supported with the interposition of at least one vibration-damping element on a bottom plate of the stationary support frame of the product chute.

A particularly simple connection results when the passive piezoelectric bending transducer is clamped or adhesively bonded in the region of its front end section to the second product guide section.

The measuring device is preferably designed to measure the bending of the passive piezoelectric bending transducer, the amplitude of the at least one voltage pulse generated by the passive piezoelectric bending transducer. With this characteristic it is easy to identify mass differences between whole and broken tablets.

In a preferred further embodiment, the device also has an evaluation unit which is designed to compare the measured values supplied by the measuring device with stored desired values.

In addition, a sorting device is preferably provided which is designed to separate good and bad tablets on the basis of the comparison result of the evaluation unit. Thus, it is possible, bad tablets before filling in the respective Dispose of container so that a subsequent elimination of containers with poorly classified tablets is no longer necessary.

In a particularly preferred embodiment, the piezoelectric bending transducer is a trimeric piezoceramic bending transducer.

Fig. 1

ist eine schematische Querschnittsansicht einer Ausführungsform der erfindungsgemäßen Vorrichtung zum Überprüfen von Tabletten in einem neutralen Zustand des Biegewandlers;

Fig. 2

ist eine schematische Querschnittsansicht der Ausführungsform aus Fig. 1 bei ausgelenktem Biegewandler;

Fig. 3

ist ein Querschnitt durch den zweiten Produktführungsabschnitt der Vorrichtung aus Fig. 1 und 2;

Fig. 4

ist eine schematische Perspektivansicht der erfindungsgemäßen Vorrichtung zum Überprüfen von Tabletten aus Fig. 1 und 2;

Fig. 5

ist eine Seitenansicht der Vorrichtung aus Fig. 4;

Fig. 6

ist eine schematische Perspektivansicht einer Seitenwange des Stützfußes für den zweiten Produktführungsabschnitt der Vorrichtung aus Fig. 5 mit piezoelektrischem Biegewandler;

Fig. 7

ist eine schematische Perspektivansicht der Seitenwange aus Fig. 6;

Fig. 8

ist ein Graph, der ein Messsignal einer Ausführungsform der erfindungsgemäßen Vorrichtung zum Überprüfen von Tabletten für eine intakte Tablette darstellt; und

Fig. 9

ist ein Graph, der ein Messsignal wie in Fig. 8, allerdings für eine gebrochene Tablette, darstellt.

Further features and advantages of the present invention will become apparent from the following description with reference to the drawings.

Fig. 1

is a schematic cross-sectional view of an embodiment of the device according to the invention for checking tablets in a neutral state of the bending transducer;

Fig. 2

is a schematic cross-sectional view of the embodiment of Fig. 1 with deflected bending transducer;

Fig. 3

is a cross section through the second product guide portion of the device Fig. 1 and 2 ;

Fig. 4

is a schematic perspective view of the device according to the invention for checking tablets Fig. 1 and 2 ;

Fig. 5

is a side view of the device Fig. 4 ;

Fig. 6

is a schematic perspective view of a side cheek of the support foot for the second product guide portion of the device Fig. 5 with piezoelectric bending transducer;

Fig. 7

is a schematic perspective view of the side cheek Fig. 6 ;

Fig. 8

Fig. 4 is a graph illustrating a measurement signal of an embodiment of the intact tablet tablet tablet validator of the present invention; and

Fig. 9

is a graph showing a measurement signal as in Fig. 8 , but for a broken tablet, represents.

As used herein, the term "tablet" is to be understood to encompass any type of small pharmaceutical product such as tablets, dragees, oblongs, capsules, and the like.

In Fig. 1 . 2 . 4 and 5 an embodiment of the device according to the invention for checking tablets is shown in different views. Usually, the device according to the invention for checking tablets is preceded by a transport device 2 for tablets. This can, as in the illustrated embodiment, for example, be configured as a vibratory conveyor with one or more webs, but may also be a feed tube or other commercially available tablet feed.

The device for checking tablets comprises a product chute 4 which has a product guide surface 6 on which the tablets 8 slide along. The product guide surface 6 is inclined for this purpose at an angle β to the horizontal. The angle β and the length of the product chute 4 are adapted to the respective prevailing conditions, for example, the manner and speed with which the tablets 8 are supplied to the product chute 4, the degree of singulation of the tablets 8 and the shape and size of the Tablets 8. In most applications, an angle β of 20 ° to 40 °, preferably 25 ° to 35 °, is advantageous.

The product chute 4 has at least one first stationary product guide section 10 and a second product guide section 12 separated therefrom and movably mounted, which together define the product guide surface 6 in a row. In the illustrated embodiment, exactly a first product guide portion 10 is present, which is significantly longer than the second product guide portion 12. The second product guide portion 12 should in any case be so short that only one tablet 8 at a predetermined time on this second product guide portion 12 slides at the same time, the second product guide section 12 should be at least as long as the largest tablet 8 to be measured.

The first product guide portion 10 has a first guide surface portion 14 (surface) on which the tablets 8 slide along. Preferably, this guide surface portion 14 formed with the contour or shape of a U-groove or V-groove to exert a centering effect on the tablets 8. The second product guide section 12 arranged at the end of the first product guide section 10 has a second guide surface section 16 (surface), which preferably has the same contour or shape as the first guide surface section 14. In this way, the tablets 8 can move unhindered from the first product guide section 10 to the second Slide product guide section 12 without their trajectory is changed. The distance a between the two product guide sections 10, 12 should be as small as possible, but must leave enough space in the illustrated preferred embodiment for an unobstructed arcuate lowering of the second product guide section 12, as will be described in more detail below. In the illustrated example, the product chute 4 comprises only one product guide surface 6, but it may also be several product guide surfaces 6 (a plurality of juxtaposed grooves) may be provided in the product chute 4.

In the illustrated embodiment, only a first product guide section 10 is shown. It is also possible to provide a plurality of stationary, first product guide sections 10 which, for example, enclose the movable second product guide section 12 between them.

The stationary first product guide section 10 is connected to a stationary support frame 18 of the product chute 4. In the illustrated embodiment, the support frame 18 is configured as a stand frame with a pillar 20 and a bottom plate 22. It is also possible that the support frame 18 has laterally projecting support arms or any other construction of a stationary attachment to any machine frame.

The second product guide section 12 is already part of a sensor integrated in the product chute 4 for detecting defective tablets during their passage through the product chute 4. In addition, the sensor has a passive piezoelectric bending transducer 24, which is connected to the second product guide section 12. When the passive piezoelectric bending transducer 24 is bent, at least one voltage pulse is generated by the bending transducer 24, as will be described in more detail below. To accommodate this voltage pulse, the passive piezoelectric bending transducer 24 is connected to a measuring device 26, which is preferably aligned thereon is to measure the amplitude of the voltage pulse generated by the passive piezoelectric bending transducer 24. The measured values supplied by the measuring device 26 are preferably forwarded to an evaluation unit 28, which compares the measured values with stored nominal values in order to check the integrity of the tablets 8. These set values are usually recorded by a calibration process for each type of tablet before the start of the respective filling process on the basis of individual, classified as well 8 tablets. For the distinction between good and bad tablets 8 a tolerance threshold is usually provided, which is adjustable by the operator in an individual case.

On the basis of the comparison result of the evaluation unit 28, it is provided in a preferred embodiment, by means of a sorting device 30 good and bad tablets 8 before their storage in the respective container (vials, blister cup, etc.) to separate. For example, the sorting device 30 may be designed as a mechanical switch or as a blow-out device, which adjoins the product chute 4 below. However, it is also possible to follow up containers that have been filled with at least one bad tablet 8 in the overall process and only at another point in the overall process, for example, only after sealing and punching the blister pack or after closing the vial with a cap, sort out.

Piezoelectric bending transducers 24 typically operate by being energized and bending in response. In the context of the present invention, this basic principle is reversed by the electrical signal generated by mechanical bending of the bending transducer 24 is received by the measuring device 26. The height of the electrical signal is an indicator of the strength of the initial deflection of the bending transducer 24. In the context of the present invention, this is used for the indirect weight determination of tablets 8. When a tablet 8 slides over the second product guide section 12, the bending transducer 24 is tilted by an angle α due to the weight of the tablet 8 (FIG. Fig. 2 ), wherein the electrical signal generated by the bending transducer 24 is substantially proportional to the deflection α.

Although there are a variety of possibilities of the geometry of the bending transducer 24 and its arrangement within the product chute 4, a preferred embodiment will now be described in more detail with reference to the drawings.

Accordingly, it is preferred if the passive piezoelectric bending transducer 24 is plate-shaped and arranged at substantially the same angle β to the horizontal as the product guide surface 6. The passive piezoelectric bending transducer 24 is then connected in the region of its front end portion with the second product guide portion 12 and in Stored immobile area of its rear end portion. In this way, it is ensured that a maximum deflection of the front end portion of the bending transducer 24 in response to the weight of a tablet 8 is achieved. The bending transducer 24 is preferably glued in the region of its front end portion with the second product guide portion 12 or, as shown in the figures, clamped by means of a clamping element 32 (see in particular Fig. 3 ). The adjustment of the mass of the second product guide section 12 or the combination of the second product guide section 12 and clamping element 32 is important for the damping behavior of the bending transducer 24. Ideally, a configuration is desired in which the bending transducer 24 reverberates as little as possible, so that the sensor in very a short time to measure the next tablet 8 ready.

Of course, the rear end portion of the bending transducer 24 may be connected to the stationary support frame 18 of the product chute 4 and secured there. However, it is advantageous for decoupling the sensor from external influences such as mechanical vibrations when the passive piezoelectric bending transducer 24 is fastened in the region of its rear end section in a support foot 34 provided in addition to the support frame 18. This support leg 34 may have at least one vibration-damping element 36 on its underside, which ensures a decoupling of the sensor from mechanical vibrations of the environment. In the illustrated embodiment, the support leg 34 is supported with the interposition of the vibration damping elements 36 on the bottom plate 22 of the support frame 18 of the product chute 4.

A preferred way of attaching the rear end portion of the flexural transducer 24 to the support leg 34 is in FIG Fig. 6 and 7 shown. Fig. 6 shows one of two side walls 38 of the support leg 34, which define a gap between them. In this case, the side walls 38 on the mutually facing inner surfaces at least one recess 40 for receiving a side surface of the passive piezoelectric bending transducer 24. It is important that the recesses 40 are dimensioned such that sufficient clearance for deflection / deflection of the front end portion of the bending transducer 24 remains. For attachment of the rear end portion of the bending transducer 24 is in the recess 40 in a rear end region an open towards the gap, substantially V-shaped clamping surface 42 (see in particular Fig. 7 ) intended. In this way, the rear end portion of the bending transducer 24 is securely clamped between the two side cheeks 38 of the support leg 34.

In Fig. 6 In addition, the electrical contacts 44 for forwarding the electrical signals of the bending transducer 24 are shown. The bending transducer 24 is configured in a preferred embodiment as a trimeric piezoceramic bending transducer, but other suitable bending transducers can be used.

To further minimize the external influences on the sensor by vibrations from the environment, a further piezoelectric bending transducer 46 is provided in the illustrated embodiment, which is disposed below the first piezoelectric bending transducer 24 and at its front end portion has a counterweight 48 which is identical to the mass occupancy of the front End portion of the first bending transducer 24, in the present example, therefore, the weight of the combination of the second product guide section 12 and clamping element 32 corresponds. The evaluation of the signal of the second bending transducer 46 takes place with the opposite sign in comparison to the first bending transducer 24, so that vibrations from the environment generate signals in the first bending transducer 24 and in the second bending transducer 46, which cancel each other out. Of course, it is advantageous in this context if the second bending transducer 46 is mounted completely identical to the first bending transducer 24. In the example shown, this means that in the support leg 34 second recesses 50 are provided with second clamping surfaces 52 for the second bending transducer 46 ( Fig. 6 and 7 ).

In Fig. 8 FIG. 2 shows an exemplary signal of a non-broken tablet 8 to be classified as good, as determined by the measuring device 26. In contrast, shows Fig. 9 a corresponding waveform of a tablet section. The evaluation of the signal is preferably carried out on the amplitude of the primary rash, but can also be done on the integral of the Erstausschlags. As previously explained, it is important that ringing of the flexural transducer 24 be minimized. In the illustrated embodiment, the sensor is already ready for measuring the next tablet 8 after about 10 ms.

Claims (14)

1. Device for inspecting tablets (8), with a product chute (4) which has a product guide surface (6) which is inclined at an angle (β) to the horizontal; and a sensor integrated into the product chute (4) for detecting faulty tablets (8) as they pass through the product chute (4); characterised in that the product chute (4) has at least a first stationary product guide section (10) and a movably mounted second product guide section (12) which is separated from the first section but which together line up to define the product guide surface (6), and the sensor has in a first product guide section (10) a passive piezoelectric bending actuator (24) which is connected to the second product guide section (12) wherein the passive piezoelectric bending actuator (24) is connected to a measuring device (26) which during bending of the passive piezoelectric bending actuator (24) measures at least one voltage pulse generated by the passive piezoelectric bending actuator (24).
2. Device according to claim 1 characterised in that the guide surface section (16) of the second product guide section (12) has the same shape as the guide surface section (14) of the first product guide section (10).
3. Device according to claim 2 characterised in that the shape of the guide surface sections (14, 16) is a U-shape or V-shape.
4. Device according to one of the preceding claims characterised in that the passive piezoelectric bending actuator (24) is plate-shaped and is arranged at substantially the same angle (β) to the horizontal as the product guide surface (6).
5. Device according to claim 4 characterised in that the passive piezoelectric bending actuator (24) is connected in the region of its front end section to the second product guide section (12) and is mounted immovable in the region of its rear end section.
6. Device according to claim 5 characterised in that the first stationary product guide section (10) of the product chute (4) is connected to a stationary support frame (18) of the product chute (4), and the passive piezoelectric bending actuator (24) is fastened in the region of its rear end section in a support foot (34) which is provided in addition to the support frame (18).
7. Device according to claim 6 characterised in that the support foot (34) has two side cheeks (38) which between them define an interspace wherein the side cheeks (38) have on mutually facing inside surfaces at least one recess (40) for receiving a side region of the passive piezoelectric bending actuator (24).
8. Device according to claim 7 characterised in that the at least one recess (40) has in a rear end region a substantially V-shaped clamping face (42) which is open towards the interspace.
9. Device according to one of claims 5 to 8 characterised in that the support foot (34) is supported with the interposition of at least one vibration-damping element (36) on a base plate (22) of the stationary support frame (18) of the product chute (4).
10. Device according to one of claims 5 to 9 characterised in that the passive piezoelectric bending actuator (24) is clamped or stuck in the region of its front end section to the second product guide section (12).
11. Device according to one of the preceding claims characterised in that the measuring device (26) is set up to measure the amplitude of the at least one voltage pulse generated by the passive piezoelectric bending actuator (24) during bending of the passive piezoelectric bending actuator (24).
12. Device according to one of the preceding claims characterised in that it has an evaluator unit (28) which is set up to compare the measured values supplied by the measuring device (26) with the stored ideal values.
13. Device according to claim 12 characterised in that it has a sorting device (30) which is set up to separate good and bad tablets (8) on the basis of the comparison result of the evaluator unit (28).
14. Device according to one of the preceding claims characterised in that the passive piezoelectric bending actuator (24) is a trimorphic piezo-ceramic bending actuator.

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