Abstract:
A method and apparatus for weighing pharmaceutical product capsules, whereby a capsule containing a pharmaceutical product is fed into a pocket to allow a measuring device to determine the weight of the pharmaceutical product and of a first portion of the capsule containing the pharmaceutical product; the pocket, and therefore the capsule, then being inverted to move the pharmaceutical product out of the first portion and into a second portion of the capsule, to allow the measuring device to determine the weight of the first portion only of the capsule.

Description:
[0001]    This application claims priority from Italian Application Serial No. BO 2013A 000430 filed Aug. 1, 2013 and incorporated herein by reference. 
         [0002]    The present invention relates to an apparatus for weighing pharmaceutical product capsules. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the pharmaceutical industry, machines are used for filling capsules with pharmaceutical products. 
         [0004]    Once filled, the capsules are transferred to weighing apparatus comprising a number of pockets, each for receiving and retaining a respective capsule. 
         [0005]    The weighing apparatus also comprises a weighing system, in turn comprising, for each pocket, a measuring device for determining the weight of the capsule and the pharmaceutical product inside it. 
         [0006]    The weighing system also comprises a processing unit for calculating the weight of the pharmaceutical product alone as the difference between the value measured by the measuring device, and a nominal value representing the weight of an empty capsule. 
         [0007]    Since the nominal empty capsule weight value memorized in the processing unit of the weighing system is a theoretical value, and the actual weight of each empty capsule actually varies within a range comprising the nominal value, known apparatuses of the above type for weighing pharmaceutical product capsules are relatively inaccurate. 
         [0008]    Very often, the actual weight of the pharmaceutical product inside each capsule may even differ from the theoretical weight calculated by the weighing system on the basis of the nominal empty capsule weight value. 
       SUMMARY OF THE INVENTION 
       [0009]    It is an object of the present invention to provide an apparatus for weighing pharmaceutical product capsules, designed to eliminate the above drawbacks and which is cheap and easy to produce. 
         [0010]    According to the present invention, there is provided an apparatus for weighing pharmaceutical product capsules, as claimed in claims  1  to  12 . 
         [0011]    The present invention also relates to a method of weighing pharmaceutical product capsules. 
         [0012]    According to the present invention, there is provided a method of weighing pharmaceutical product capsules, as claimed in claims  13  and  14 . 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    A non-limiting embodiment of the present invention will be described by way of example with reference to the attached drawings, in which: 
           [0014]      FIG. 1  shows a schematic front view, with parts removed for clarity, of a preferred embodiment of the apparatus according to the present invention; 
           [0015]      FIG. 2  shows a schematic, partly sectioned side view, with parts removed for clarity, of a detail of the  FIG. 1  apparatus; 
           [0016]      FIGS. 3   a  and  3   b  show two schematic cross sections, with enlarged details and with parts removed for clarity, of a first detail in  FIG. 2  in two different operating positions; 
           [0017]      FIG. 4  shows a schematic, partly sectioned view in perspective of a second detail in  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    With reference to  FIGS. 1 ,  3   a  and  3   b , number  1  indicates as a whole an apparatus for weighing capsules  2 , each of which comprises a bottom shell  3 , and a top shell  4  closing bottom shell  3 , and contains a pharmaceutical product  5 , in particular in the form of powder or granules, of a smaller volume than capsule  2 . 
         [0019]    Apparatus  1  comprises an elongated weighing bar  6  which extends in a horizontal direction  7  and has a longitudinal axis  8  parallel to direction  7 . 
         [0020]    Bar  6  is parallelepiped shaped with a substantially rectangular cross section, and is bounded by two opposite, parallel lateral faces  9 ,  10 . 
         [0021]    Bar  6  comprises a first set of pockets  11 , which are aligned in direction  7 , open outwards at face  9 , and have respective longitudinal axes  12  crosswise to axis  8  and perpendicular to face  9 . 
         [0022]    Bar  6  comprises a second set of pockets  13 , which are aligned in direction  7 , open outwards at face  10 , and have respective longitudinal axes  14  parallel to axes  12  and perpendicular to face  10 . 
         [0023]    Pockets  13  are oriented with their concavities facing the opposite way to those of pockets  11 , and are located on the opposite side to pockets  11  with respect to a longitudinal plane of symmetry, perpendicular to faces  9  and  10 , of bar  6 . 
         [0024]    Each pocket  11 ,  13  is bounded laterally by a cylindrical bushing  15  which is fitted inside pocket  11 ,  13 , coaxially with relative axis  12 ,  14 , and comprises a wide portion  16  for receiving and retaining a capsule  2 , and a narrow portion  17 . 
         [0025]    Bar  6  also has two air manifolds  18 ,  19  formed through bar  6  and parallel to direction  7 ; manifold  18  communicates with portions  17  of bushings  15  of pockets  11 ; and manifold  19  communicates with portions  17  of bushings  15  of pockets  13 . 
         [0026]    Each pocket  11 ,  13  has a capacitive transducer  20  integrated in relative bushing  15  and which, together with capacitive transducers  20  of the other bushings  15 , forms part of a weighing system  21  also comprising a processing unit  22  connected to capacitive transducers  20 . 
         [0027]    Bushings  15  and capacitive transducers  20  are described and illustrated in the Applicant&#39;s Patent Application WO-2006/035285-A2, the content of which is included as a whole in the present patent application. 
         [0028]    Each free end of bar  6  is connected to a respective rotary supporting arm  23  with the interposition of two shock-absorbing devices  24  mounted crosswise to direction  7 . 
         [0029]    Shock-absorbing devices  24  allow two vibrating devices  25  to shake bar  6 , pockets  11 ,  13 , and therefore capsules  2  housed inside the pockets  11 ,  13 , as described more clearly below. 
         [0030]    Each device  25  comprises an electromagnet  26 , which is interposed between a relative free end of bar  6  and a relative arm  23 , and which is designed to vibrate bar  6  according to a given law of motion. 
         [0031]    Bar  6 , arms  23 , shock-absorbing devices  24  and vibrating devices  25  are moved as a whole intermittently about axis  8  by an actuating device—in the example shown, an electric motor—connected to one of arms  23 . 
         [0032]    Pockets  11 ,  13  in each set of pockets  11 ,  13  are moved back and forth between a first operating position, in which the concavities of pockets  11 ,  13  face upwards with relative axes  12 ,  14  parallel, to a vertical direction  28  crosswise to direction  7 , and a second operating position, in which the concavities of pockets  11 ,  13  face downwards with relative axes  12 ,  14  parallel to direction  28 . 
         [0033]    In other words, pockets  11  are in the first operating position when pockets  13  are in the second operating position ( FIG. 3   a ), and pockets  13  are in the first operating position when pockets  11  are in the second operating position ( FIG. 3   b ). 
         [0034]    Apparatus  1  also comprises a known hopper  29  mounted over bar  6  and designed to feed a capsule  2 , oriented in the example shown with top shell  4  on top of bottom shell  3 , into each pocket  11 ,  13  in the set of pockets  11 ,  13  in the first operating position. 
         [0035]    Operation of apparatus  1  will now be described with reference to  FIGS. 2 ,  3   a ,  3   b  and  4 , with reference to pockets  11  only, and as of the instant in which: 
         [0036]    pockets  11  are in the first operating position ( FIG. 3   a ); 
         [0037]    hopper  29  releases a capsule  2  into each pocket  11 ; and 
         [0038]    manifold  18  is connected to a pneumatic suction device (not shown) to retain capsules inside respective pockets  11 . 
         [0039]    Once capsules  2  are fed into pockets  11 , the two electromagnets  26  are activated to shake pockets  11 , detach the pharmaceutical product  5  from the lateral walls of capsules  2 , and ensure all the pharmaceutical product  5  settles at the bottom of capsules  2 . 
         [0040]    At this point, the two electromagnets  26  are deactivated, and capacitive transducer  20  of each pocket  11  determines the weight of relative pharmaceutical product  5 , and of a first portion  30  of relative capsule  2 , which contains pharmaceutical product  5  and is of at least the same volume as pharmaceutical product  5  (in the example shown, the volume of first portion  30  over-approximates the volume of pharmaceutical product  5 ). 
         [0041]    Next, bar  6  is rotated about. axis  8  by actuating device  27  to move pockets  11  into the second operating position ( FIG. 3   b ); and the two electromagnets  26  are activated to shake pockets  11 , detach pharmaceutical product  5  from the lateral walls of capsules  2 , and ensure all the pharmaceutical product  5  settles at the bottom of capsules  2 . 
         [0042]    By rotating bar  6  and activating the two electromagnets  26 , the pharmaceutical product  5  in each capsule  2  drops by gravity into a second portion  31  of capsule  2 , which is of at least the same volume as pharmaceutical product  5 , so as to completely empty the corresponding first portion  30 . 
         [0043]    At this point, the two electromagnets  26  are deactivated, and capacitive transducer  20  of each pocket  11  determines the weight of first portion  30  of relative capsule  2  only. 
         [0044]    Finally, processing unit  22  calculates the difference between the first value measured by each capacitive transducer  20  with pockets  11  in the first operating position, and the second value measured by each capacitive transducer  20  with pockets  11  in the second operating position, so as to determine with absolute precision the net weight of pharmaceutical product  5  inside each capsule  2 . 
         [0045]    With reference to  FIGS. 2 and 4 , manifold  18  is disconnected from the pneumatic suction device and connected to a pneumatic compressed-air device (not shown) to transfer each capsule  2  from relative pocket  11  to a relative unloading conduit  32  extending beneath bar  6  and comprising two outlet channels  33 ,  34 . 
         [0046]    In response to a signal from processing unit  22 , each capsule  2  is fed selectively into one of the two channels  33 ,  34  by a diverting device  35  mounted to rotate, about a hinge axis  36  parallel to direction  7 , between a first operating position ( FIGS. 2 and 4 ), in which diverting device  35  opens channel  33  and closes channel  34 , and a second operating position (not shown), in which diverting device  35  opens channel  34  and closes channel  33 . 
         [0047]    In other words, when the weight of pharmaceutical product  5  calculated by processing unit  22  equals a threshold value or falls within a given range, capsule  2  is fed along conduit  33 ; and conversely, when the weight of pharmaceutical product  5  calculated by processing unit  22  differs from the threshold value or does not fall within said given range, capsule  2  is fed along conduit  34  and rejected. 
         [0048]    Apparatus  1  is highly precise, by virtue of weighing system  21  determining both the actual weight of pharmaceutical product  5  and first portion  30  of capsule  2  (i.e. the gross weight), and the actual weight of first portion  30  of capsule  2  only (i.e. the tare), and calculating the actual weight of pharmaceutical product  5  inside capsule  2  (i.e. the net weight) as the difference between the two measurements. 
         [0049]    In other words, the actual weight of pharmaceutical product  5  inside each capsule  2  is calculated as the difference between two actual weights, both measured by capacitive transducer  20 , as opposed to the difference between an actual weight measured by capacitive transducer  20  and a nominal weight (the weight of capsule  2 ) memorized in processing unit  22 . 
         [0050]    Obviously, in variations not shown: 
         [0051]    each capsule  2  may be transferred from hopper  29  into relative pocket  11 ,  13  with top shell  4  beneath bottom shell  3 ; 
         [0052]    each capsule  2  may be oriented inside relative pocket  11 ,  13  to allow weighing system  21  to weigh pharmaceutical product  5  and second portion  31  first, and then weigh second portion  31  only.