Patent Publication Number: US-6335960-B2

Title: Detection of variable manufacturing tolerance packages utilizing x-rays

Description:
CROSS REFERENCE 
     The present application is a continuation of U.S. application Ser. No. 09/420,163 filed Oct. 18, 1999, now U.S. Pat. No. 6,215,845. 
    
    
     BACKGROUND 
     The present invention generally relates to the detection of missing components in a package, particularly to an x-ray scanner and processing system for detecting missing components in a package, and specifically to an x-ray scanner and processing system for detecting missing components which can have a variety of positions within a package. 
     A number of products are marketed in the form of multiple components which are included within a sealed package, with the consumer removing the components from the package at a location remote from the point of purchase and combining those components to form the final product. As the components are located within the package, the manufacturer as well as the consumer are unable to verify whether or not the package includes all components until after the package is opened. As many products are now mechanically packaged, packages where all the components are not there, where multiple components are present, and like deficiencies will be created depending upon machinery reliability. As such packaging errors are a major cause of consumer complaints especially when packages do not include all the necessary components to produce the final product, there exists a need for systems to detect whether the proper components are present in the package without requiring the opening of such packages. 
     One manner of such detection is by weighing the final package after sealing. This suffers from several shortcomings including reliability of correctly weighing the individual packages as they are being conveyed on a conveyor. Similarly, the weight of a component may be such that if one component were omitted (or a duplicate included), the package including the remaining components would be within the range of weights for the package including all components manufactured within the normal manufacturing tolerances. 
     Also, the components could be manufactured including identifiers which can be sensed outside of the package. However, it can then be appreciated that this has limitations in the number of identifiers which can be included in a single package and still be separately identifiable, typically requires extra manufacturing steps, and results in false negatives as the components could be present in the package but either the identifiers were omitted or could not be sensed from outside of the package. 
     X-ray scanning systems have had wide commercial success in the detection of contaminants in a package. Typical applications would be detecting metal in food products, bone portions in fillets, lumps or clumps in powdered or semi fluid components, or the like. Although prior x-ray scanning systems have been utilized for detecting missing components, use of x-ray scanning systems were generally limited to packages where the components are in a consistent position within the packages. Example packages would include egg cartons, TV dinners, and the like. 
     X-ray scanning detection systems are desirable for several reasons including but not limited to they do not require use of identifiers, do not require any modifications to the production line upstream from the detection system, do not leave marks or have the potential of damaging the sealed package and the like. Thus, a need exists for an x-ray scanning system which is able to detect which packages include one or more missing components where the components can have a variety of arrangements or positions within the package and which do not generate a substantial number of false negatives. 
     SUMMARY 
     The present invention solves this need and other problems in the field of package x-ray detection systems and methods by, in the most preferred form, comparing the combined value of a multiplicity of outputs of radiation detectors corresponding to areas of a package with a standard value for a package including all desired components and rejecting any packages having package values that do not meet the standard value. In the most preferred form, the multiplicity of outputs are generated by moving the packages on a conveyor between a fan shaped beam x-ray radiator and a row of detectors. 
     It is thus an object of the present invention to provide a novel x-ray scanner and processing system. 
     It is further an object of the present invention to provide such a novel x-ray scanner and processing system which is not orientation dependent. 
     It is further an object of the present invention to provide such a novel x-ray scanner and processing system especially useful for detecting missing components in a package where the components can have a variety of positions or arrangements inside of the package. 
     It is further an object of the present invention to provide such a novel x-ray scanner and processing system substantially eliminating the generation of false negatives. 
     Other objects and advantages of the invention will become apparent from the following detailed description of an illustrative embodiment of this invention described in connection with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The illustrative embodiment may best be described by reference to the accompanying drawings where: 
     FIG. 1 shows a diagrammatic view of an x-ray scanner and processing system according to the preferred teachings of the present invention. 
     FIG. 2 shows a cross sectional view of a representative package scanned by the system of FIG.  1 . 
     FIG. 3 shows an array of illustrative numerical outputs generated by the system of FIG. 1 scanning a package of the type represented by FIG.  2 . 
     FIG. 4 shows a graphical depiction generated by prior systems scanning a package of the type represented by FIG.  2 . 
     FIG. 5 shows a cross sectional view of another representative package scanned by the system of FIG.  1 . 
     FIG. 6 shows an array of illustrative numerical outputs generated by the system of FIG. 1 scanning a package of the type represented by FIG.  5 . 
     FIG. 7 shows a graphical depiction generated by prior systems scanning a package of the type represented by FIG.  5 . 
    
    
     All figures are drawn for ease of explanation of the basic teachings of the present invention only; the extensions of the figures with respect to number, position, relationship and dimensions of the parts to form the preferred embodiment will be explained or will be within the skill of the art after the following description has been read and understood. Further, the exact dimensions and dimensional proportions to conform to specific force, weight, strength, and similar requirements will likewise be within the skill of the art after the following description has been read and understood. 
     DESCRIPTION 
     An x-ray scanner and processing system according to the preferred teachings of the present invention is shown in the drawings and generally designated  10 . System  10  includes an x-ray radiator  12  which generates energy waves in the form of a fan-shaped x-ray beam  14  encompassing and irradiating packages  16  on a conveyor  18 . The plane of the fan shaped x-ray beam  14  is perpendicular to the conveying direction, with the conveying direction extending out of the plane of the drawing. The radiation passing through package  16  and conveyor  18  is received by a line or row array  20  comprised of a plurality of individual detectors  20   a ,  20   b , etc. For purposes of explanation, it will be assumed that eleven individual detectors  20   a ,  20   b , etc. extend across the width of package  16  on conveyor  20 . In actuality, the number of individual detectors  20   a ,  20   b , etc. is in the order of 256 to 512. Likewise, for purposes of explanation, a numerical reference is given to the output of each of the individual detectors  20   a ,  20   b , etc., with the larger number indicating that a greater amount of radiation is being received by the individual detectors  20   a ,  20   b , etc. In the following description, when package  16  is not positioned between x-ray radiator  12  and array  20 , the maximum output of the individual detector  20   a ,  20   b , etc. is 255. It can then be appreciated that if package  16  is positioned between radiator  12  and array  20 , the output of the individual detectors  20   a ,  20   b , etc. will be less than 255 depending upon the particular composition to the material in the plane of x-ray beam  14 . As an example, if metal were positioned in between radiator  12  and any particular detector  20   a ,  20   b , etc. in the plane of beam  14 , the output of those particular detectors  20   a ,  20   b , etc. would be 0 as no radiation would be detected. However, it can be appreciated that the numerical value is entirely arbitrary and a matter of choice. As an example, the value could be based upon the amount of radiation blocked, with the numerical value of 0 indicating no radiation is being blocked and a positive number such as but not limited to 100 indicating that 100% of the radiation is being blocked. The same principles are involved no matter what numerical values are assigned to the outputs of the individual detectors  20   a ,  20   b , etc. 
     It should further be appreciated that beam  14  is generated in cycles by radiator  12  and in the most preferred form is generated at approximately 700 cycles/second. Thus, as package  16  is conveyed on conveyor  18  and moved between radiator  12  and array  20 , individual detectors  20   a ,  20   b , etc. generate a multiplicity of outputs corresponding to distinct areas of package  16 . In the most preferred form, package  16  takes about one half second to pass entirely through the plane of beam  14  such that 350 readings are made across package  16 . 
     It should then be appreciated that system  10  as described thus far is of a conventional design (see as an example U.S. Pat. No. 4,788,704). Historically, such systems  10  were utilized to detect contaminants in package  16 . As an example, if the output of one or more individual detectors  20   a ,  20   b , etc. indicated that no radiation was being detected at any time that package  16  including food was in the plane of beam  14 , package  16  was rejected because such an indication indicated the undesired presence of metal. Such rejection typically is in the form of removal from conveyor  18  by suitable means  30  such as but not limited to removal by air jets, grabbing or pushing arms, moveable conveyor sections or the like. In addition to metals, system  10  could be utilized to detect other contaminants such as but not limited to the presence of a bone in a fillet, or the like, where the amount of radiation being detected by the individual detectors  20   a ,  20   b , etc. was less than the range of amount normally detected by the individual detectors  20   a ,  20   b , etc. Use of system  10  for detecting contaminants in packages  16  has historically been very successful in these applications. 
     In addition to the presence of unwanted components, the next progression of system  10  was to detect the absence of missing components. Specifically, packages  16  often include multiple components  22 ,  23 , and  24 . As an example, component  22  could be a pouch including a base such as pasta, component  23  could be a pouch including a sauce such as a tomato sauce, and component  24  could be a pouch including a topping such as a cheese. Prior to the present invention, system  10  utilized the same threshold detection in determining whether components were missing as when contaminants were present. Specifically, it was assumed that if the components  22 - 24  were present, the amount of radiation being detected would be less than when one or more components  22 - 24  were missing. Thus, if the amount of radiation that was detected by detectors  20   a ,  20   b , etc. was less than a threshold amount, it was assumed that the components  22 - 24  were present. Use of system  10  in this manner is fairly successful if components  22 - 24  and package  16  had consistent positioning, in other words everything in package  16  was regimented and stationary relative to package  16 . As an example, packages  16  in the form of egg cartons including individual components  22 - 24  in the form of eggs held in their own compartments and always passing through the plane of beam  14  in the same orientation can be successfully scanned by system  10  to detect the absence of one or more individual eggs from package  16 . Specifically, if one or more individual eggs were missing from package  16 , the radiation detected by array  20  would be greater than for packages  16  where individual eggs are not missing and could be rejected by system  10 . In this regard, detection of missing components  22 - 24  having consistent positioning inside of package  16  can be successfully accomplished using a threshold mode of operation where if a threshold amount of radiation reduction is detected, it can be assumed that the components  22 - 24  are there, and additionally if a greater amount of radiated reduction is detected, it can be assumed that a contaminant is present. 
     It can be appreciated that if packages  16  passed through the plane of beam  14  in a different orientation, the radiation reduction detected by the individual detectors  20   a ,  20   b , etc. would not be the same between the individual packages  16 . However, the orientation of packages  16  entering system  10  can be easily mechanically controlled to be consistent. The problem arises when components  22 - 24  can have a variety of positions or are allowed to move inside of package  16 . Specifically, the radiation reduction detected by the individual detectors  20   a ,  20   b , etc. would not be the same with components  22 - 24  at various positions inside of package  16 . 
     With this as background, the method of detecting missing components  22 - 24  from package  16  according to the teachings of the present invention can be explained and differentiated from prior methods in connection with a package  16  including three components  22 - 24 . For purposes of explanation, it is desirable to have components  22 - 24  in a vertical stacked arrangement on conveyor  18  in the position shown in FIG. 2 with base component  22  located intermediate components  22  and  24  and with component  23  located closest to conveyor  18 . It can be appreciated that when mechanically positioned in and sealed within package  16 , components  22 - 24  will be in the desired arrangement about 90% of the time. However, about 10% of the time, for whatever reason, components  22 - 24  do not have the desired orientation. An example of another possible orientation is shown in FIG. 6 wherein components  23  and  24  are in a side-by-side arrangement adjacent to conveyor  18  and component  22  is stacked on and straddles components  23  and  24 . 
     FIG. 3 represents an array of a multiplicity of numerical outputs of the individual detectors  20   a ,  20   b , etc. as package  16  including components  22 - 24  in the arrangement of FIG. 2 passes through the plane of beam  14 . It should be appreciated that the array is merely illustrative for the sake of simplicity as only  11  readings are provided in each row across the width of package  16  corresponding to  11  individual detectors  20   a ,  20   b , etc. when in actuality a multiple of times that number of individual detectors  20   a ,  20   b , etc. are provided. Similarly, only 16 readings are provided in each column across the length of package  16  corresponding to the number of cycles of radiator  12  when in actuality a multiple of times that number of cycles are provided. Based upon an x-ray value of 255 where no reduction in radiation is detected and considering the lowest value detected by the individual detectors  20   a ,  20   b , etc. in the line array  20  or considering the value detected by an individual detector  20   a ,  20   b , etc. generally located in the center of the width of package  16 , a reduction in the radiation is detected as the paperboard or other material forming package  16  passes through the plane of beam  14 , which reduction is indicated by the numerical output of  230 . Further reduction in radiation is detected as component  23  passes through the plane of beam  14 , and then components  22  and  23  pass through the plane of beam  14 , and then all three components  22 - 24  pass through the plane of beam  14 . It can be appreciated that the reduction in detected radiation will be the greatest when the plane of beam  14  simultaneously passes through all three components  22 - 24 , with the actual reduction of radiation being dependent upon several factors including the particular consistency of the material within components  22 - 24 , the particular thickness of components  22 - 24  and the like, with the greatest reduction in radiation in the example having a numerical output of  24 . As package  16  continues to travel through the plane of beam  14 , there is less reduction in radiation as the end of component  23  passes through the plane of beam  14 , and lesser still as the end of component  24  passes through the plane of beam  14 , and even lesser still as the end of component  22  passes through the plane of beam  14  and beam  14  again only passes through the material forming package  16 . It should be appreciated that the individual detectors  20   a ,  20   b , etc. do not have the same numerical outputs, but the radiation detected by any particular detector  20   a ,  20   b , etc. and the numerical output will be dependent on the particular position of the particular detector  20   a ,  20   b , etc. in array  20 , with the detectors  20   a ,  20   b , etc. adjacent the edges of package  16  and components  22 - 24  typically experiencing less radiation reduction than detectors  20   a ,  20   b , etc. in the center of package  16 . 
     FIG. 4 represents a graphical representation that would be displayed utilizing prior methods for the numerical outputs of the array of FIG.  3 . In particular, the lowest numerical value (representing the greatest reduction in radiation) is plotted for each successive reading as package  16  passes through beam  14 . As this numerical value is below a threshold value indicated as the numerical value of 45 in FIG. 4, this particular package  16  would pass the scanning test of system  10  and would not be rejected thereby. In this regard, the numerical value does not pass a minimal value such as being equal to 0 which would indicate the presence of a contaminant, which would be a reason that system  10  would reject package  16 . 
     FIG. 6 represents an array of numerical outputs of individual detectors  20   a ,  20   b , etc. as package  16  which includes components  22 - 24  in the arrangement of FIG. 5 passes through the plane of beam  14  utilizing the same parameters as set forth for FIG.  3 . Based upon an x-ray value of 255 where no reduction in radiation is detected and considering the lowest value detected by the individual detectors  20   a ,  20   b , etc. in the line array  20  or considering the value detected by an individual detector  20   a ,  20   b , etc. generally located in the center of the width of package  16 , a reduction in the radiation is detected as the paperboard or other material forming package  16  passes through the plane of beam  14 , which reduction is indicated by the numerical output of 230. Further reduction in radiation is detected as component  23  passes through the plane of beam  14 , and then components  22  and  23  pass through the plane of beam  14 . However, as package  16  continues to travel through the plane of beam  14 , there is less reduction in radiation as the end of component  23  passes through the plane of beam  14  and beam  14  passes only through component  22 . Greater reduction in radiation is again detected as the end of component  24  passes through the plane of beam  14  and beam  14  passes through both components  22  and  24 . There is less reduction in radiation as the end of component  22  passes through the plane of beam  14  and lesser still as the end of component  24  passes through the plane of beam  14  and beam  14  again only passes through the material forming package  16 . In this example, beam  14  never passes simultaneously through components  22 - 24  and thus the reduction in radiation of package  16  of FIG. 6 is lesser than the maximum reduction in detected radiation of package  16  of FIG.  2 . 
     FIG. 7 represents a graphical representation that would be displayed utilizing prior methods for the numerical outputs of the array of FIG.  6 . In particular, the lowest numerical value (representing the greatest reduction in radiation) is plotted for each successive reading as package  16  passes through beam  14 . As this numerical value is always above a threshold value indicated as the numerical value of 45 in FIGS. 4 and 7, this particular package  16  would fail the scanning test of system  10  and would be rejected by the rejection means  30  of system  10 . However, package  16  of FIG. 5 includes all  3  components  22 - 24  , and system  10  would have provided a false negative. In actual practice, about one half of the 10% of the packages  16  which contain all  3  components  22 - 24  but not in the desired arrangement of FIG. 2 are falsely rejected as not including all components  22 - 24 . This is an amount which makes system  10  utilizing prior methods commercially unacceptable for detecting missing components  22 - 24  in packages  16 . 
     The present invention is the recognition that the outputs of the individual detectors  20   a ,  20   b , etc. of array  20  can be utilized in a manner which was not previously considered and/or which was considered inoperable to arrive at a commercially acceptable method for detecting missing components  22 - 24  in packages  16 . In particular, it was recognized that although the manner that radiation is reduced is dependent upon the arrangement of components, the total amount of radiation which is absorbed by components  22 - 24  as well as the material forming package  16  is generally dependent upon mass of the particular components and the amount of mass does not change with the arrangement of components  22 - 24 . According to the methods of the present invention, the multiplicity of electrical outputs of individual detectors  20   a ,  20   b , etc. is combined to arrive at a combined value by suitable means diagramatically designated in FIG. 1 as  26 . It can then be appreciated that the sum of all the values of each of the individual detectors  20   a ,  20   b , etc. of array  20  of all of the successive readings as package  16  passes through beam  14  provides a representation of the combination of the electrical values of radiation absorbed by components  22 - 24  and the material forming package  16  located in discreet volumes represented by individual blocks in the arrays of FIGS. 3 and 6, with the amount of radiation being absorbed being directly related or in other words a representation of the mass of components  22 - 24  and package  16  in those discreet volumes. 
     According to the teachings of the present invention, the combined value is compared with a standard value by suitable means diagramatically designated in FIG. 1 as  28 . The standard value is identified by scanning and obtaining combined values of packages  16  including all components  22 - 24  within the normal manufacturing tolerance ranges. In this regard, the standard value would be in the form of a range for acceptable products. The standard value could be variable and float according to the particular operating parameters including but not limited to the environment temperature, relative humidity, and the like. 
     As shown in FIG. 3, the total sum of values of the numerical outputs of the individual detectors  20   a ,  20   b , etc. for all of the successive readings as package  16  of FIG. 2 passes through beam  14  is 22398 which is equal to the total sum of values of the numerical outputs of the individual detectors  20   a ,  20   b , etc. for all of the successive readings as package  16  of FIG. 7 passes through beam  14 , even through the numerical outputs for particular detectors  20   a ,  20   b  etc. are not the same in the arrays of FIGS. 3 and 6. The total sum of values is then set to encompass normal manufacturing tolerances from a desired package  16  including the desired weight and makeup of components  22 - 24  . 
     There are several reasons why it is believed that persons skilled in the art did not consider utilizing the total amount of radiation which is absorbed as a criteria in testing packages  16 . First, this method of the present invention does not provide testing for contaminants, the initial reason why system  10  was developed. In particular, although the numerical outputs of particular detectors  20   a ,  20   b , etc. for particular readings could be beyond the prior thresholds, the total sum of values could be within an acceptable range for the desired total. Thus, it is believed that the mindset of those skilled in the art was that this criteria would not useful in testing packages for contaminants and thus would not be useful in testing packages per se. Although recognizing this deficiency, the method of the present invention is a recognition that x-ray system  10  can be utilized in a different manner to achieve results which were not previously considered or considered inoperable. In this regard, testing for contaminants in addition to the method of the present invention is contemplated including but not limited to the utilization of prior x-ray contamination methods in parallel with the methods of the present invention and even utilizing the same outputs of the individual detectors  20   a ,  20   b , etc. but for multiple purposes. 
     Additionally, the method of the present invention does not lend itself to graphical depiction as do the prior methods as depicted in FIGS. 4 and 7. In particular, although a single value for each successive reading of array  20  has significance and can be easily graphically displayed, the successive readings of array  20  has no significance in the method of the present invention as only the total value of the readings representing the total amount of radiation absorbed has significance. Thus, graphical depiction is not needed, and only a counter type gauge  32  showing the total value of the readings is the only type of visual indication necessary, if desired. 
     Further it should be appreciated that unlike mass, absorption of x-rays is position dependent. As an example, the absorption of x-rays is subject to a Bernoulli Equation as to distance. It can then be appreciated that the distance of components  22 - 24  from radiator  12  are different in packages  16  shown in FIGS. 2 and 5, and thus the rate of absorption of x-rays by components  22 - 24  as sensed by the individual detectors  20   a ,  20   b , etc. in the packages  16  of FIGS. 2 and 5 will be different. Due to this non-linear relationship and the belief that this would prevent any meaningful use of an indication of the total amount of x-ray absorption, its use prior to the present invention had not been considered or had been considered inoperable by persons skilled in the art. However, it was discovered that in the ranges necessary to operate system  10  according to the methods of the present invention that a person skilled in computer processing can easily develop an algorithm which converts the values of detectors  20   a ,  20   b , etc. to approximate a linear relationship to allow the total sum of values to have a practical and meaningful significance in the method of the present invention in the detection of missing components  22 - 24  in package  16 . The method of the present invention is then proceeding opposite to conventional thinking in the field of x-ray detection systems. 
     Although not illustrated, it can be clearly appreciated that if one or more components  22 - 24  were missing from package  16 , the prior method would not reach its threshold value and the total sum of values would not be within the acceptable range of the method of the present invention. Thus, both methods would result in a rejection of package  16  which omitted one or more components  22 - 24  by any suitable means such as but not limited to an air jet diagramatically designated in FIG. 1 as  30 . 
     Similarly, system  10  can be utilized in the method of the present invention to detect if individual components  22 - 24 , although present, are not within the desired manufacturing weight tolerances. In particular, it should be appreciated that if components  22 ,  23 , or  24  are present in a greater amount than desired, the radiation detected will be less and if present in a lesser amount than desired, the radiation detected will be greater. This variation (outside of a normal tolerance range) can be detected by system  10  according to the teachings of the present invention. Thus, the line check weigher scales utilized in prior production lines could be eliminated utilizing system  10  of the present invention and especially for small weight components could have greater reliability than prior conveyor scales. 
     Similarly, in the most preferred form system  10  could be utilized to check for contaminants in parallel with the methods for checking for missing components of the present invention. Thus, metal detectors and other component checking equipment could be eliminated. 
     Those skilled in the art will further appreciate that the present invention may be embodied in other specific forms without departing from the spirit or central attributes thereof. In that the foregoing description of the present invention discloses only exemplary embodiments thereof, it is to be understood that other variations are contemplated as being within the scope of the present invention. Accordingly, the present invention is not limited in the particular embodiments which have been described in detail therein. Rather, reference should be made to the appended claims as indicative of the scope and content of the present invention.