EP2923958B1 - Device for adapting the control of a system for processing foil webs - Google Patents

Description

The invention relates to a device for adjusting the control of a system for processing film webs, in particular a blister machine.

In the pharmaceutical packaging industry, medicines such as tablets or capsules are packed in blister packs. A blister pack consists of a molded film formed in the blister machine and a cover film sealed onto the mold film after the mold film has been filled. These films are supplied by the manufacturer on rolls, so are available as film webs. To minimize downtime, the respective film web end is connected in the production process at the end of the roll, for example by means of an adhesive tape, in abutment with the beginning of the new roll. The exact position of this splice must be known to the blister machine. With this information, appropriate measures such as non-shaping of the film web in the region of the splice, non-filling of the film web in the region of the splice, as well as excretion of the affected blister packs are initiated after punching at various workstations of the blister machine.

For the detection of such splice sites, ultrasound systems are currently preferably used in cover film webs, wherein applied adhesive strips cause increased damping at the splice sites. However, this does not work with the usually much thicker film webs, since here the thickness ratio of film web to tape can be up to 1:10 and thus the thin compared to the film web adhesive tape in measurement noise goes down. For this reason, optical systems in the form of contrast sensors are used in the case of film webs, for example.

Both ultrasound systems and optical systems require format change, i. the conversion of the system to another product to be packaged and thus also to changed film properties, are taught to the new film and splice material. This is time-consuming and represents a risk in terms of pharmaceutical safety.

In particular, optical systems reach their limits with printed and highly reflective film. Furthermore, there is the possibility that film web rolls of individual spliced film webs are produced. If the film manufacturer now uses a material deviating from the taught-in adhesive tape, recognition can become impossible. In the case of optical scanning, moreover, in the case of non-transparent film webs, two recognition systems for front and back of the film web are required, since a splice can be applied to both the front side and the back side of the film web.

US 2010/290885 A1 shows, for example, a generic device for adjusting the control of a system for processing film webs. Splices are optically detected in the film web and control commands for the workstations are adjusted based on splice detection.

In addition, known in the art Wegmesser for measuring film thicknesses.

Finally shows US 4,583,669 a Wegmesser for the detection of splices in tape cassettes. The path signal determined by the sensor is processed and amplified in various ways, but not differentiated.

The present invention has for its object to provide a device for adjusting the control of a system for processing film webs, in particular a blister machine, provide that is pharmaceutically safe and also forms a format-independent, not einzulernendes system.

According to the invention, the device for adjusting the control of a system for processing film webs, in particular a blister machine, comprises a central control device, which is designed to supply a plurality of workstations of the system with control commands, and a device for detecting splices in the film web. The device for detecting splice sites in the film web has a displacement meter which has a measuring element which is mechanically movable as a function of a thickness of the film web and which is designed to generate a sensor signal depicting the thickness of the film web. In addition, the device for detecting splices an analog evaluation, which is connected to the odometer and receives the sensor signals of the odometer, the analog evaluation at least one differentiator for differentiating the sensor signals and for generating voltage signals corresponding to the speed of the measuring element, and also a comparator connected downstream of the differentiator for comparing the voltage signals output by the differentiator with at least one predetermined limit value. The analog evaluation unit outputs decision signals on the basis of the comparison to the control device, and the control device is adapted to adapt the control commands for the work stations on the basis of the decision signals of the analog evaluation unit.

With this configuration, it is possible to ensure a reliable detection of the splices even with clocked movements of the film web. In addition, the system does not have to be re-taught when changing the type of film or the type of splice. With the described system, a detection of splice sites on both the front and the back of the film web to be monitored is also ensured. The analog evaluation is based on a differentiation of the sensor signals of the odometer, whereby only sudden changes caused by an edge of a splice, are recognized as relevant for decision. Temporally slower processes such as production-related changes in the film thickness are thereby masked out.

In a preferred embodiment, the comparator is designed as a window comparator. In this case, it is possible to further process voltage signals of the differentiator as a positive decision criterion, which lie in either the positive or negative direction outside a symmetric, stored around zero window area. In this way, both the rising edge and the falling edge of a splice can be detected with the same odometer.

To improve the signal quality of the rectangular signals supplied by the comparator and to increase the signal strength, the analog evaluation unit preferably has a pulse shaping circuit connected downstream of the comparator.

In a preferred embodiment, the analog evaluation unit also has a function monitoring device. This is used to operationally monitor the mobility of the mechanical components, the integrity of the sensor cable and the sensor functionality.

Preferably, the measuring element is guided in a plain bearing. This results in a smooth running behavior during the movement of the measuring element.

In a preferred embodiment, the displacement sensor is designed as an inductive analog sensor, which comprises a sensor element in addition to the measuring element, wherein the measuring element of the odometer is designed as an approximate element which is mounted vertically displaceable relative to a transport direction relative to the sensor element. Thus, the sensor element itself has no moving parts wearing, which has a positive effect on the life and availability of the system.

With further advantage, the sensor element and the measuring element are inductively operatively connected such that a change in the distance between the measuring element and the sensor element causes a change in the damping of the sensor element by the measuring element. This results in an improved measurement dynamics, which in turn increases the measurement reliability.

If the measuring element has a roller mounted in its lower region, which rolls on the film web, the contact between the measuring element and the film web is ensured without the risk of damaging the film web.

In a particularly preferred embodiment, a second displacement sensor is arranged in a transport direction of the film web downstream of the first displacement meter. The control device is designed to evaluate the sensor signals of the two odometer and to adjust the control commands for the workstations based on the evaluation of the sensor signals. This redundant system ensures that even with extremely slow film speeds, as they can occur with clocked machines during the ramps or down ramps of each clock, yet a secure detection is guaranteed because at least one of the two odometer splice each time detected, to which the film web already or still has a sufficient speed for the evaluation.

It is advantageous if the distance between the first odometer and the second odometer in the transport direction of the film web is between 10 and 50 mm, preferably between 15 and 30 mm. This has the advantage that both odometer in the same Holder can be stored and also the correlation between the sensor signals of the two odometer can easily take place.

Fig. 1

ist ein schematisches Diagramm des Aufbaus einer Ausführungsform der erfindungsgemäßen Vorrichtung zur Anpassung der Steuerung einer Anlage zur Bearbeitung von Folienbahnen;

Fig. 2a und 2b

sind eine Querschnittsansicht und eine Frontansicht eines bevorzugten mechanischen Aufbaus des Wegmessers;

Fig. 2c

ist eine Ansicht des Messelements;

Fig. 2d

ist eine Ansicht des Sensorelements; und

Fig. 3

zeigt Blockschaltbilder von bevorzugten Ausgestaltungen der einzelnen Baugruppen der analogen Auswerteeinheit.

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

Fig. 1

is a schematic diagram of the structure of an embodiment of the device according to the invention for adjusting the control of a system for processing film webs;

Fig. 2a and 2b

FIG. 4 is a cross-sectional view and a front view of a preferred mechanical structure of the odometer; FIG.

Fig. 2c

is a view of the measuring element;

Fig. 2d

is a view of the sensor element; and

Fig. 3

shows block diagrams of preferred embodiments of the individual modules of the analog evaluation unit.

In the Fig. 1 schematically illustrated apparatus for adjusting the control of a system for processing of film strips, in particular a blister machine, comprises a displacement sensor 2, which generates a curve of the thickness of the film strip 4 imaging sensor signals, and an analog evaluation unit 6 which is connected to the odometer 2 and the Sensor signals of the odometer 2 receives. In the illustrated example case, the odometer 2 and the analog evaluation unit 6 together form a device for detecting splices 8 in the film strip 4.

The analog evaluation unit 6 for the odometer 2 comprises a low-pass filter 14, a differentiator 10 for differentiating the sensor signals and also a comparator 12 connected downstream of the differentiator 10 for comparing the voltage signals output by the differentiator 10 with at least one predetermined limit value.

The sensor signals of the displacement meter 2, which map the course of the thickness of the film strip 4, are generated in a stationary sensor element 48. In this case, the sensor element 48 generates signals which depend on the distance between the sensor element 48 and a measuring element 32 which can be moved up and down mechanically. The measuring element 32 moves up and down depending on the thickness of the film strip 4, when the film strip 4 is moved below the fixedly mounted sensor element 48 in a transport direction T (see Fig. 2a ). When differentiating the sensor signals, the differentiator 10 thus generates voltage signals which correspond to the speed of the measuring element 32.

The analog evaluation unit 6, on the basis of the comparison made by the comparator 12, sends decision signals to a central control device 16, which is designed to supply a plurality of workstations of the blister machine with control commands. The control device 16 will adjust the control commands generated by it for the workstations on the basis of the decision signals of the analog evaluation unit 6. Specifically, this means that certain subsequent operations such as the molding of Blesternäpfen, the filling of these blister pens with tablets, etc. at the locations of the film strip 4, where splice 8 were detected, are not performed. In addition, such portions of the film strip 4, the splice 8 have, at the end of the processing steps, i. after punching the individual blisters from the sealed film web 4, are excreted.

The voltage signal supplied by the comparator 12 usually already has an approximate rectangular shape. In order to obtain a reproducible rectangular signal of defined pulse width, the analog evaluation unit 6 may have a comparator 12 connected downstream of the pulse shaping circuit 18. Via a switching output 20 of the analog evaluation electronics 6, the square-wave signal thus enters the central control device 16.

In the illustrated preferred embodiment, the analog transmitter 6 may further comprise a function monitoring device 22, which preferably also has a comparator 13, a pulse shaping circuit 19 and an associated switching output 21. The sensor signal generated by the sensor element 48 has a certain interference signal during operation due to the running noise and machine vibrations transmitted by the measuring element 32. In case of an error, such as a wire break, a Sensor defect or a mechanical blockage of the sliding bearing 36, this interference signal falls below the set in the comparator 13 threshold. In this way it is ensured that the sensor signals supplied by the sensor element 48 are authentic, the connection to the differentiator 10 is intact and the mechanical transmission of the thickness of the film strip 4 is ensured. The function monitoring device 22 also sends its output signal to the central control device 16.

Referring to Fig. 2a to 2d Now, a preferred embodiment of Wegmessern 2 will be described in more detail. In this example, two odometer 2 on a bracket 28 ( Fig. 2b Fixed, which includes a projecting in the horizontal direction holding plate 30 for the two odometer 2. In the illustrated example of the Fig. 2a to 2d are the two odometer 2 in the transport direction T of the film web 4 at a distance of preferably between 10 and 50 mm, more preferably between 15 and 30 mm, respectively. In the present embodiment, the two odometer 2 are arranged in series parallel to the transport direction T of the film web 4, but it is also conceivable to offset the two Wegmesser 2 in addition to the offset in the transport direction T of the film web 4 also transversely to the transport direction T of the film web 4.

Both odometer 2 are each associated with an analog evaluation unit 6. The structure of the circuit of the analog evaluation unit 6 for the second odometer 2 is basically identical to the structure of the circuit of the first odometer 2 according to Fig. 1 ,

By the second odometer 2 ensures that a splice 8 always passes through at least one of the two odometer 2 with required minimum speed. The background to this is that blister machines in the area of film forming, which follows the detection area, are generally operated clocked, so that depending on the machine speed, the film web 4 is stopped about 20 to 60 times per minute and set in motion again. If a splice point 8 now comes to a stop directly in front of a displacement gauge 2, the generated sensor signal may be too low for reliable detection, in particular given a slow machine speed and / or a splice point 8 facing away from the measuring element 32. The binary signals of the two channels generated in the respective electronic evaluation unit 6 are correspondingly logically linked and further processed in such a case. The two-channel design also represents a redundant system with correspondingly increased reliability.

As in Fig. 2c A measuring element 32 preferably consists of a measuring element housing 54 and an approximate plunger 40. The measuring element housing 54 is designed as an elongate housing with a cavity, and the proximity plunger 40 is designed as a pin-shaped element which is displaceably mounted in the measuring element housing 54. An end portion of the proximity rod 40 extends through an opening which is formed on the upper end side of the measuring element housing 54. As continues in Fig. 2c can be seen, the proximity rod 40 by a spring 56 which may be designed as a coil spring, be biased towards the upper end face of the measuring element 54 with respect to the measuring element housing 54.

Each measuring element 32 is guided on each sliding bearing 36, preferably a linear slide bearing, displaceable up and down. The plain bearings 36 are in Fig. 2a and 2b shown only schematically; There are also many other types of bearings of the measuring element 32 conceivable.

In the lower region of each measuring element 32, a roller 38, preferably a spherical stainless steel roller is mounted, which rolls on the film web 4.

In this embodiment, the proximity plunger 40 forms the object whose distance to the sensor element 48 is measured by the sensor element 48. However, many other embodiments of the measuring element are conceivable.

Referring to Fig. 2d the sensor element 48 is likewise designed as a vertically arranged elongated element and arranged above the measuring element 32. In the region of its lower end, the sensor element 48 has an oscillator 58, which generates an alternating electromagnetic field by means of a resonant circuit. This alternating field exits from the lower active surface 60 of the sensor element 48. In the front approaching measuring element 32 made of metal eddy currents are induced, which deprive the oscillator 58 energy. This results in the output of the oscillator 58, a level change, which affects the analog output signal of the sensor element 48 as a function of the distance between the measuring element 32 and the sensor element 48. The level change at the output The oscillator is typically processed and amplified by a signal converter 62 and an output amplifier 64, thus producing the output signal of the sensor element 48.

The operating stroke range of the measuring element 32 is preferably limited to the small non-contact measuring range of the sensor element 48. As already indicated above, when the measuring element 32 is raised beyond the operational stroke range, the proximity plunger 40 is pressed by the distance sensor 48 into the measuring element housing 54. Mechanical stops 42 on the plain bearings 36 limit this stroke, so that the axial force on the odometer 2 does not exceed the predetermined by the spring constant of the spring 56 force.

A bracket 28 ( Fig. 2b ) connects the support plate 30 for the odometer with the preferably made of stainless steel foil guide 44 and serves at the same time for mounting the device on the machine frame. Preferably, the film guide 44 is provided with rounded edges. At the film inlet and film outlet of the sensor system baffles 46 are preferably mounted to calm the film movement. The outlet-side baffle 46 additionally assumes the function of a thermal shielding of the odometer 2 with respect to the following in the film running direction T heated mold station in which the blister pens are formed in the film web 4.

Provided that a corresponding movement profile of the film strip 4 and a minimum width of the splice 8 are complied with, only one odometer 2 can be provided for reliable detection of splices 8. It is therefore clear that instead of the previously described two odometer 2, there is also the possibility of using only one odometer 2. In this case, the structure of the one odometer 2 is identical to the structure of each of the two odometer 2 described above.

With reference to Fig. 3 Now essential components of the analog transmitter 6 will be described in more detail.

The differentiator 10 realized by means of the operational amplifier IC11b is the core of the circuit. The analog, the position of the measuring element 32 corresponding voltage signal A1 (0-10 V) is converted here into a voltage signal corresponding to the speed of the measuring element 32. Previously, the sensor signal passes through an active low-pass filter around IC11a, which suppresses high-frequency interference pulses, caused by electromagnetic interference. C14 and R15 form the time constant, R14, together with R15, determines the gain of the negating operational amplifier circuit, and at the same time, stabilizes against oscillation tendency towards higher frequencies. A sudden increase in the input signal (movement of the displacement sensor 2 on the splice 8 at the rising edge of the splice 8) leads to a negatively polarized voltage peak at the output of IC11b. A movement of the odometer 2 of the splice 8 down (falling edge of the splice 8) accordingly causes a positive polarized voltage spike. In the diagram these pulse shapes are sketched on the trimming potentiometers P21 and P22 belonging to the window comparator described below.

The comparator 12 is designed as a window comparator and consists of two circuit parts around the comparators IC21a and IC21b. Here, the voltage peaks output by the differentiator 10 are monitored for limit values. Only correspondingly high, real splices 8 corresponding signals are recognized as such and smaller, e.g. suppressed by machine vibration caused signals. The limit values are set with the trim potentiometers P21 and P22 to values between -1.0 and 0 V (P22) and 0 and +1.0 V (P21). This unique setting is valid regardless of the film web 4 used for all imaginable splice 8. IC21a thus monitors positive voltage spikes (movement from splice 8 down), IC21b correspondingly negative spikes (movement up to splice 8). The outputs of the comparators IC21a and IC21b can signal equal positive or negative limit value overshoots in the present circuit. If only one of the two edges (rising or falling) is to be monitored, a simple comparator can also be used instead of the window comparator.

The pulse shaping circuit 18 comprises a timer IC31a, which converts the variable pulse width of the switching signal generated by the window comparator into a square wave signal having a fixed pulse duration. C32 determines the pulse duration (about 100 ms). The LED D31 signals the good status "no splice point" (green). The transistor T31 generates the control signal required for the machine, which passes to the central control unit 16. For the corresponding level adjustment, this transistor is supplied with the internal machine voltage L + (24 VDC). D33 provides reverse polarity protection of the binary output, D32 assumes the overvoltage protection of the transistor output. The series resistor R34 limits the output current and thus acts as overload protection.

In addition to the components mentioned, the analog evaluation unit 6 can also have a device 22 for monitoring function. The device 22 for monitoring the function comprises a comparator 13, a pulse shaping circuit 19 and a switching output 21. This structure essentially corresponds to the structure of the splice branch. The interference signal, which is transmitted to the displacement sensor 48 by running disturbances of the film strip 4 and machine vibrations, is hereby interpreted as a life signal. The switching thresholds of the comparator 13 are set correspondingly lower. Timer IC31b is connected in contrast to the timer IC31a with its negated switching output. In the operational state of the machine it is assumed that one of the switching thresholds of the comparator 13 per machine cycle is triggered at least once. Accordingly, the time constant is dimensioned via C52 to a value greater than the duration of the slowest machine cycle. Accordingly, the signal Fkt before machine start is at low level, which is equivalent to a fault condition. The central control device 16 must logically link this circumstance so that the actual monitoring function is activated by the control device 16 only after the end of the first machine cycle after the machine has been started.

The dual power supply of the analog evaluation unit 6 is generated via a DC / DC converter from the machine-internal supply voltage.

Examples of the embodiment of in Fig. 3 Components shown are listed in the following list: Low Pass Filter 14 / Differentiator 10 IC11 2-fold operational amplifier (eg LM 358) C11 Capacitor 180-470 pF C12 Capacitor 100-330 pF C13 Capacitor 180-470 pF C14 Capacitor 330 nF-2.2 μF C15 Capacitor 1.0-4.7 nF Cs Backup capacitors 47-220 nF R11 Metal film resistance 3.3-10 kΩ R12 Metal film resistance 3.3-10 kΩ R13 Metal film resistance 1.0-4.7 kΩ R14 Metal film resistance 0.47-2.2 MΩ R15 Metal film resistance 0.47-2.2 MΩ Comparator splice 12 IC21 4-fold comparator (eg LM 339) Cs Support capacitors 47-220 nF ceramic P21 Multi-turn potentiometer 3,3-22 kΩ P22 Multi-turn potentiometer 3,3-22 kΩ R21 Metal film resistance 33-220 kΩ R22 Metal film resistance 1.8-6.8 kΩ R23 Metal film resistance 22-100 kΩ R24 Metal film resistance 1.8-6.8 kΩ R25 Metal film resistance 22-100 kΩ R26 Metal film resistance 33-220 kΩ Comparator Function Monitoring 13 P41 Multi-turn potentiometer 3,3-22 kΩ P42 Multi-turn potentiometer 3,3-22 kΩ R41 Metal film resistance 33-220 kΩ R42 Metal film resistance 1.8-6.8 kΩ R43 Metal film resistance 22-100 kΩ R44 Metal film resistance 1.8-6.8 kΩ R45 Metal film resistance 22-100 kΩ R46 Metal film resistance 33-220 kΩ Pulse shaping splice 18 IC31 Precision monoflop (eg CD 4538) T31 Transistor PNP (eg BC 327) D31 LED green D32 Zener diode (eg ZPD 36) D33 Diode (eg 1 N 4148) C31 Capacitor 47-220 nF C32 Tantalumko 3.3-22 μF Cs Support capacitor 47-220 nF ceramic R31 Metal film resistance 1.0-4.7 kΩ R32 Metal film resistance 33-220 kΩ R33 Metal film resistance 1.8-6.8 kΩ R34 Metal film resistance 0.68-3.3 kΩ R35 Metal film resistance 33-220 kΩ R36 Metal film resistance 0.47-2.2 MΩ Pulse shaping Function monitoring 19 T51 Transistor PNP (eg BC 327) D51 LED green D52 Zener diode (eg ZPD 36) D53 Diode (eg 1 N 4148) C51 Capacitor 47-220 nF C52 Tantalumko 3.3-22 μF Cs Support capacitor 47-220 nF ceramic R51 Metal film resistance 1.0-4.7 kΩ R52 Metal film resistance 33-220 kΩ R53 Metal film resistance 1.8-6.8 kΩ R54 Metal film resistance 0.68-3.3 kΩ R55 Metal film resistance 33-220 kΩ R56 Metal film resistance 0.47-2.2 MΩ

In the case of two displacement meters 2, two circuits are as in Fig. 3 available.

The odometer 2 does not have to be designed as an inductive distance sensor, but it is also possible to use other known displacement meters which work, for example, with an optical detection of a mechanically moved punch.

The sensor signals of the sensor element 48 are usually between 0 and 10 V DC.

The sensor element 48 can also generate current signals as sensor signals instead of voltage signals.

With regard to the detection of splice sites 8, the described device is not subject to any restrictions. It detects splices 8 in all types and thicknesses of film webs 4, preferably aluminum or plastic films, and is suitable for detection in clocked operation. Also irrelevant are the type of bonding and the arrangement of the thickening on the top or bottom of the monitored film web. 4

Claims (12)

1. Device for adapting the control of a system for processing foil webs (4), more particularly a blister machine, with
   a central control device (16) which is set up to supply a plurality of work stations of the system with control commands, and
   a device for detecting the splicing positions (8) in the foil web (4),
   characterised in that
   the device for detecting the splicing stations (8) has a position measuring device (2) which has a measuring element (32) which is movable mechanically dependent on the thickness of the foil web (4) and which is set up to generate sensor signals representing a profile of the thickness of the foil web (4)
   that the device for detecting the splicing stations (8) furthermore has an analog evaluating unit (6) which is connected to the position measuring device (2) and receives the sensor signals from the position measuring device (2), wherein the analog evaluation unit (6) has at least one differentiator (10) for differentiating the sensor signals and for generating voltage signals corresponding to the speed of the measuring element (32), and furthermore a comparator (12) connected to the output side of the differentiator (10) for comparing the voltage signals issued by the differentiator (10) with at least one predetermined limit value,
   that the analog evaluation unit (6) issues decision-making signals, based on the comparison, to the control device (16) and
   that the control device (16) is set up to adapt the control commands for the work stations based on the decision-making signals of the analog evaluation unit (6).
2. Device according to claim 1 characterised in that the comparator (12) is a window comparator.
3. Device according to claim 1 or 2 characterised in that the analog evaluation unit (6) has an impulse-forming circuit (18) connected to the output of the comparator (12).
4. Device according to one of the preceding claims characterised in that the analog evaluation unit (6) has a device (22) for monitoring the functions.
5. Device according to claim 4 characterised in that the measuring element (32) is guided by means of a sliding bearing (36).
6. Device according to one of the preceding claims characterised in that the position measuring device (2) is designed as an inductive analog sensor which comprises a sensor element (48) in addition to the measuring element (32), wherein the measuring element (32) of the position measuring device (2) is designed as a proximity element which is mounted displaceable relative to the sensor element (48) vertically in relation to a transport direction (T).
7. Device according to claim 6, characterised in that the sensor element (48) and the measuring element (32) are in active inductive connection so that a change in the distance between the measuring element (32) and the sensor element (48) causes a change in the damping of the sensor element (48) by the measuring element (32).
8. Device according to one of the preceding claims characterised in that a sensor signal issued by the position measuring device (2) is an analog signal.
9. Device according to claim 8 characterised in that the measuring element (32) has a roller (38) which is mounted in the lower region thereof and which rolls along the foil web (4).
10. Device according to one of the preceding claims characterised in that the analog evaluation unit (6) has a low-pass filter (14) connected in to the input of the differentiator (10).
11. Device according to one of the preceding claims characterised in that a second position measuring device (2) is arranged in a transport direction (T) of the foil web (4) downstream of the first position measuring device (2), and that the control device (16) is set up to evaluate the sensor signals of the two position measuring devices (2) and to adapt the control commands for the work stations on the basis of the evaluation of the sensor signals.
12. Device according to claim 11 characterised in that the distance between the first position measuring device (2) and the second position measuring device (2) in the transport direction (T) of the foil web (4) is between 10 and 50 mm, preferably between 15 and 30 mm.

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