Abstract:
The invention relates to a device ( 10; 10   a ) for determining the weight of pharmaceutical products ( 1 ), in particular of hard gelatin capsules ( 3; 3   a ) filled with a pharmaceutical ( 2 ), by means of an X-ray source (28), wherein the X-ray source ( 28 ) generates a radiation cone ( 27; 36, 37 ) which passes through at least one pharmaceutical product ( 1 ), and wherein a sensor element ( 30; 30   a ) detects the radiation of the irradiated pharmaceutical product ( 1 ) and supplies an evaluation device ( 32 ). According to the invention, a reference object ( 35; 35   a;    35   b ) is arranged in the beam path of the radiation cone ( 27; 36, 37 ), wherein the radiation of the X-rayed reference object ( 35; 35   a;    35   b ) is detected by means of the sensor element ( 30; 30   a;    30   b ) and is supplied to the evaluation device ( 32 ), and wherein the pharmaceutical product ( 1 ) and the reference object ( 35; 35   a;    35   b ) are positioned in relation to the radiation cone ( 27; 36, 37 ) in an arrangement in which they do not overlap each other in the radiation cone ( 27; 36, 37 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a device for determining the weight of pharmaceutical products by means of an X-ray source. The invention furthermore relates to a method for determining the weight by means of a device in accordance with the invention. 
         [0002]    A device is known from the German patent specification DE  10   2009   045   809  Al of the applicant. The known device comprises an X-ray source, which serves to determine the weight of products filled with a pharmaceutical, in particular in the form of hard gelatin capsules. In this case, the pharmaceutical product is X-rayed by the X-ray source and the radiation which penetrates the pharmaceutical object is detected by means of an image recording sensor element. An evaluation device of the aforementioned device then determines a filling weight for the pharmaceutical product from, e.g., the detected grey scale values of the image of said pharmaceutical product. The disadvantage with this process is that due to changing conditions, the values detected by the sensor element vary from image to image for one and the same pharmaceutical product. A concrete association of the image or respectively gray scale values with a certain filling weight in the capsule is thus made more difficult. In the case of consecutively recorded images, changes of this kind can only be recognized at locations whereat an unimpeded radiography is possible. The changes cannot however thereby be unambiguously compensated, particularly when detecting the filling weight by means of grey scale values. 
       SUMMARY OF THE INVENTION 
       [0003]    Based on the previously described prior art, the aim underlying the invention is to further develop a device for determining the weight of pharmaceutical products by means of an X-ray source such that disturbances due to fluctuations in the overall system as well as external disturbances can be detected and compensated for, and therefore a particularly high degree of accuracy with regard to determining the weight of the pharmaceutical products is achieved. According to the invention, the aim is met by a device for determining the weight of pharmaceutical products by means of an X-ray source, said device having the features of claim  1 , in that a reference object is arranged in the beam path of the radiation cone, wherein the radiation of the irradiated reference object is detected and supplied to the evaluation device, and wherein the pharmaceutical product and the reference object are positioned in relation to the radiation cone in an arrangement in which they do not overlap each other in the radiation cone. That is to say when imaging or respectively X-raying the pharmaceutical product, a reference object is also always simultaneously X-rayed; and therefore in combination with reference object, the items of image information can be reliably associated with the gray scale values of the pharmaceutical product even when fluctuations in the overall system or those caused by external disturbances occur. A particularly exact determination of the weight of the pharmaceutical product can thereby be performed. 
         [0004]    Advantageous modifications to the inventive device for determining the weight of pharmaceutical products by means of an X-ray source are specified in the dependent claims. All combinations from at least two features disclosed in the claims, the description and/or the figures fall within the scope of the invention. 
         [0005]    Provision is made in a preferred embodiment of the invention for the sensor element to be designed as an image recording sensor element. Using such an image recording sensor element, the pharmaceutical product to be examined can be very easily divided up into image points (pixels), from which items of information for the evaluation device can be obtained via the gray scale values in order to determine the weight of the pharmaceutical product. 
         [0006]    An embodiment of the reference object, in which the material of said reference object has a similar atomic composition as the pharmaceutical product, is particularly preferred. The same physical properties as for the pharmaceutical product thus result when X-raying the reference object, and therefore the obtained items of image information about the reference object can be used directly for determining the weight of the pharmaceutical product without complicated conversions or correction factors. 
         [0007]    An embodiment of the invention is furthermore preferred, in which the reference object is arranged in the same plane as the pharmaceutical product. In so doing, preconditions for the radiography which are at least approximately the same are created for the reference object and the pharmaceutical product with respect to the radiation cone or the X-ray radiation. 
         [0008]    In order to be able to produce different gray scale values on the recorded image by means of the reference object, provision is made in a preferred manner for the reference object to have different thicknesses in a plane perpendicular to the beam path of the X-ray source. Different gray scales are produced by means of said different thicknesses in the image of the X-rayed reference object, which is detected by the sensor element. 
         [0009]    Such gray scales can be constructively produced in a particularly simple and reproducible manner by means of the reference object if said reference object is designed in steps or wedge-shaped. In this way, discrete gray scales can be achieved on the image of the X-rayed reference object by means of a stepped configuration, wherein the number of steps or respectively stairs should be selected as large as possible in order to improve the resolution or to increase the measuring accuracy. As an alternative, a wedge-shaped reference object can also be used, which continually produces varying gray scale values by means of the wedge-shaped form thereof 
         [0010]    In order to be able to evaluate all detected gray scale values or respectively gray scale levels of the X-rayed pharmaceutical product, provision is furthermore made in a particularly preferred manner for the reference object to produce a damping of the X-rays, which is larger at one location and smaller at another location than the damping produced by the pharmaceutical product. In so doing, it is ensured that all gray scale values normally occurring when X-raying the pharmaceutical product are covered by means of the reference object. 
         [0011]    In order to maximize the individual steps of the reference object or respectively the surface thereof in a stepped or wedge-shaped configuration, provision is furthermore made in a particularly preferred manner for the surface of the reference object to be perpendicularly aligned to the radiation cone. 
         [0012]    The invention also comprises a method for determining the weight of pharmaceutical products by means of a device according to the invention. Provision is thereby made for the pharmaceutical product and the reference object to be simultaneously X-rayed by means of an X-ray source, for an image of the X-rayed pharmaceutical product and the reference object to be supplied to the evaluation device by means of at least one image recording sensor element, for the evaluation device to examine the X-rayed pharmaceutical product pixel by pixel for the gray scale value thereof, for the same gray scale value on the reference object and thereby a thickness of the reference object to be associated with the respective pixel, for a virtual volume of the pharmaceutical product to be calculated thereafter in knowledge of the number and the surface area of the pixels and in a final step with the aid of the average thickness for the virtual volume of the pharmaceutical product to be multiplied by the thickness of pharmaceutical product in order to determine the weight of said pharmaceutical product. 
         [0013]    A method is particularly preferred, in which the gray scale values of the reference object in consecutive images are compared with each other. In the case of a deviation, a correction factor is applied to the current gray scale values of the reference object. It is thereby ensured that the device readjusts itself even in the case of a lengthy operation thereof, in which parameters change as a result of a change in the overall system or external disturbances. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments as well as on the basis of the drawings. 
           [0015]    In the drawings: 
           [0016]      FIG. 1  shows a simplified longitudinal section of a device for determining the weight of hard gelatin capsules, 
           [0017]      FIG. 2  shows a simplified top view of a device, which is modified with respect to  FIG. 1 , utilizing reference objects according to the invention, 
           [0018]      FIGS. 3 and 4  show in each case simplified sections through different embodiments of a reference object according to the invention and 
           [0019]      FIG. 5  shows an image of the device pursuant to  FIG. 2 , which is recorded by means of an image recording sensor. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The same components or components having the same function are provided with the same reference numerals in the figures. 
         [0021]    In  FIG. 1 , the basic design of a device  10  for determining the weight of pharmaceutical products  1  is depicted. The pharmaceutical products  1  in this case relate particularly to hard gelatin capsules filled with a pharmaceutical and as the case may be with auxiliary substances or additives. It is however also within the scope of the invention to determine the weight, e.g., of tablets or something similar using the device. 
         [0022]    The device  10  comprises an impeller  12  which is rotated in a vertical axis of rotation in discrete steps and is only depicted in part in  FIG. 1 . A plurality of receptacles, which receive respectively one pharmaceutical product, are vertically aligned and are designed as bore holes, are located on the upper side of said impeller, wherein only one receptacle can be seen in  FIG. 1 . A through bore-hole having a smaller diameter than the receptacle  13  is configured at the base of said receptacle  13 . 
         [0023]    During a standstill phase of said impeller  12 , at least one receptacle  13  is positioned beneath a tubular conveyor shaft  15  by means of the progressively rotated impeller  12 . On the side facing the receptacle  13 , the conveyor shaft  15  comprises a section having a reduced diameter, the diameter of which is dimensioned such that a hard gelatin capsule situated in the region of the section  16  is in force-locking connection with said section  16 , i.e. is clamped in said section  16 . Beneath the through-bore hole, an insertion plunger  18  which moves up and down corresponding to the double-headed arrow  17  is arranged on the side facing away from the conveyor shaft  15 . The hard gelatin capsule  3  situated in each case in the receptacle  13  is pushed out of the receptacle thereof  13  over into a region above the section  16  of the conveyor shaft  15  so that the impeller  12  can be further rotated in order to dispense the next hard gelatin capsule(s) without the hard gelatin capsule  3 , which was last pushed over into the conveyor shaft  15 , falling downwards out of said conveyor shaft  15  as a result of the weight force thereof. 
         [0024]    The conveyor shaft  15  has a cross section, which is adapted to the cross section of the hard gelatin capsule  3  or rather somewhat larger than this. In the exemplary embodiment, the conveyor shaft  15  or respectively the longitudinal axis thereof is vertically arranged together with the longitudinal axes  19  of the hard gelatin capsules. A flap  22 , which can be pivoted back and forth corresponding to the double-headed arrow  21 , is arranged at the upper end of the conveyor shaft  15 , said flap delivering the respective hard gelatin capsule  3  that has been pushed out of the conveyor shaft  15  either to a first discharge channel  23  or a second discharge channel  24 , depending on the position of the flap  22 . In so doing, those hard gelatin capsules, which are evaluated as “good” hard gelatin capsules  3 , are conveyed further via the first discharge channel  2 ; whereas those hard gelatin capsules  3 , which are evaluated as “bad” hard gelatin capsules  3 , are conveyed further via the second discharge channel  24 . 
         [0025]    The conveyor shaft  15  comprises a section  26  which is permeable to x-radiation in a somewhat central region. The section  26  is radiographed by the radiation cone  27  of an X-ray source, the central radiation axis of which is preferably but not restrictively horizontally aligned, i.e. runs perpendicularly to the longitudinal axis  19 . A detector in the form of an image recording sensor element  30 , which is connected via a cable  31  to the evaluation device  32 , is arranged on the side of the section  26  opposite to the X-ray source  28 . The evaluation device  32  simultaneously serves to at least indirectly actuate the position of the flap  22 . 
         [0026]    The weight of the pharmaceutical  2  in the hard gelatin capsule  3  is determined by means of the X-ray source  28 , the sensor element  30  and the evaluation device  32  in combination with a reference object  35 , which is to be explained later in greater detail and which cannot be seen in  FIG. 1  because it is situated in a plane perpendicular to the drawing plane of  FIG. 1 . Therefore (besides if need be other criteria), the result serves the purpose of distinguishing “good” hard gelatin capsules  3  from “bad” hard gelatin capsules  3 . 
         [0027]    The modified device  10   a  depicted in  FIG. 2  differs from  FIG. 1  by the fact that the device  10   a  has two X-ray sources arranged next to one another, the radiation cones  36 ,  37  of which in each case simultaneously pass through a plurality of hard gelatin capsules  3 , in the exemplary embodiment respectively six hard gelatin capsules  3 , as well as in each case a reference object  35 . Two separate image recording sensor elements  30   a  are thereby arranged on the side of the hard gelatin capsules  3  opposite to the X-ray sources  28  so that each of the sensor elements  30   a  is associated with an X-ray source  28 . 
         [0028]    Of course, it is also within the scope of the invention for both X-ray sources  28  to use a common image recording sensor element  30   a.    
         [0029]    The one reference object  35 , which is associated with the radiation cone  36 , is situated in the top view at the left edge region of the radiation cone  36 , while the other reference object  35 , which is associated with the radiation cone  37 , is situated on the right edge of the radiation cone  37 . It can furthermore be seen that the two reference objects  35  are located with respect to the respective radiation cone  36 ,  37  in the same plane as the hard gelatin capsules  3  to be radiographed. It is also important that the arrangement of the reference objects  35  in the respective radiation cone  36 ,  37  is configured in such a way that the reference objects  35  and the hard gelatin capsules  3  do not overlap each other. 
         [0030]    Different embodiments of a reference object  35   a ,  35   b  are depicted in  FIGS. 3 and 4 . The reference object  35   a ,  35   b  advantageously consists of a material which has similar atomic properties as the pharmaceutical product  1  to be radiographed, i.e. particularly has the same damping properties for the x-radiation. It can furthermore be seen that both reference objects  35   a ,  35   b  have different thicknesses with regard to their cross sections. Whereas the reference object  35   a  is thereby designed wedge-shaped, the reference object  35   b  has a series of steps  38 , which cause a discrete change in the thickness of the reference object  35   b . Provision is preferably made for the damping (gray scale value) of the reference object  35   a ,  35   b  to be greater at one location and smaller at another location than the damping by means of the pharmaceutical product  1 . The arrangement or respectively the alignment of said reference objects  35   a ,  35   b  with respect to the radiation cone  36 ,  37  is furthermore configured in such a way that said reference objects  35   a ,  35   b  are arranged perpendicularly to their surface facing the X-ray source  28 , i.e. perpendicularly to the steps  38  of said reference object  35   b  or perpendicularly to the base  40  of said wedge- shaped reference object  35   a.    
         [0031]    As is especially apparent in  FIG. 2 , the arrangement of the reference object  35   a ,  35   b  in the respective edge region of the radiation cone  36 ,  37  is therefore configured such that said reference object  35   a ,  35   b  has to be disposed in each case somewhat obliquely in order to facilitate the previously addressed perpendicular radiographing or respectively X-raying of the reference object  35   a ,  35   b.    
         [0032]    By means of the previously addressed geometric configuration of the reference objects  35   a ,  35   b , said objects have different thicknesses, which produce different gray scale values at the sensor element  30  when radiographing with the X-ray source  28 . In this connection, reference is made to  FIG. 5 , in which the images of the device  10   a  pursuant to  FIG. 2 , which are recorded via two sensor elements  30   a , are depicted in a simplified manner. Both reference objects  35   b , which are configured in steps in the exemplary embodiment depicted, can be seen on the left or the right image edge. It is also apparent that the individual steps  38  have different gray scale values. A plurality of hard gelatin capsules  3  containing the pharmaceutical  2 , which likewise has a certain gray scale value, can furthermore be seen in each respective section of the image 
         [0033]    The determination of the weight of the pharmaceutical  2  situated in a hard gelatin capsule  3  is explained below as follows: An image of the reference object  35   a ,  35   b  is recorded in a calibration process, which has previously taken place and is not depicted, and the gray scale values thereof detected by the sensor device  30 ,  30   a  are associated with the thicknesses of the reference object  35   a ,  35   b  on the basis of the known geometric configuration of said reference object  35   a ,  35   b . In other words, this means that a certain thickness of said reference object  35   a ,  35   b  at a certain location is inferred on the basis of a certain gray scale value of said reference object  35   a ,  35   b . Furthermore, based on the known geometry and the known material properties of said reference object  35   a ,  35   b , a certain density can thereby be associated with a certain gray scale value of said reference object  35   a ,  35   b.    
         [0034]    These gray scale values previously determined in the calibration process as well as the geometric association thereof with the reference object  35   a ,  35   b  are stored in the evaluation device  32 . 
         [0035]    If, for example, the weight of the pharmaceutical  2  of the hard gelatin capsule denoted in  FIG. 5  with the reference numeral  3   a  is now detected or respectively checked, the image of the hard gelatin capsule detected by the sensor element  30   a  is divided up into individual image points (pixels). Each pixel represents a certain surface area, for example a square having an edge length of 100 μm. Then the detected gray scale value of the pixel is associated with an (identical) gray scale value on the reference object  35   a ,  35   b  for every pixel of the hard gelatin capsule. A certain thickness can be associated with said gray scale value (on the basis of the association of the thicknesses with the gray scale values on the reference object  35   a ,  35   b ). After this process has taken place pixel by pixel, an average thickness is determined from the individual thicknesses. Said average thickness is now multiplied by the overall number of pixels and the known surface area thereof, and therefore a virtual volume of the pharmaceutical  2  can be determined. With knowledge of the density of the pharmaceutical  2 , the weight of the pharmaceutical  2  situated in the hard gelatin capsule  3   a  can finally be determined from the virtual volume. 
         [0036]    It is also essential for an image of the relevant reference object  35   a ,  35   b  to be recorded in each case at the same time that the pharmaceutical product  1  is being x-rayed. In so doing, changes in the gray scale values on the reference object  35   a ,  35   b  can be determined on temporally consecutive images. Said changes can occur as a result of disturbances in the system or as a result of external interferences. Should, for example, it be determined that the gray scale value of the reference object  35   b  changes at a certain step, the evaluation device  32  can then subject said detected, current gray scale value to a correction factor, which adapts the current gray scale value to the original gray scale value and consequently compensates for the interferences. 
         [0037]    The devices  10 ,  10   a  described to this point can be altered or modified in many ways without deviating from the thought underlying the invention. It is, however, important for the image of a reference object  35 ,  35   a ,  35   b  to in each case be simultaneously recorded when measuring the weight of the pharmaceutical product  1 , said image being used to determine the weight of the pharmaceutical product  1 . It is thus, for example, conceivable for the pharmaceutical products  1  not to be radiographed in a direction which runs perpendicularly to the longitudinal axis  19  thereof. The reference object  35 ,  35   a ,  35   b  can also basically be arranged in any position in the beam path of the X-ray source  28 .