Abstract:
An inspection device for inspecting a granular product includes a feed tray having a receiving region for receiving the granular product and an imaging region and a vibration device configured to impart vibrations to the feed tray for moving granules of the granular product from the receiving region to the imaging region. The inspection device also includes an image capturing device configured to capture an image of a sample of the granular product in an image area of the imaging region. In addition, a method for inspecting a granular product includes disposing the granular product on a receiving region of a feed tray, vibrating the feed tray so as to induce a movement of the granular product from the receiving region of the feed tray to an imaging region of the feed tray, and capturing an image of a sample of the granular product in an image area of the imaging region.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates generally to an inspection device and method, and more particularly to a device and method for inspecting a granular product.  
           [0002]    In the production granular products including powders, there is a desire to inspect the product to determine various qualities of the product, such as size, shape and color characteristics of the granules and the presence and quantity of any impurities, as well as characteristics of those impurities. Other qualities that may be desired to be determined include flow characteristics of the granules and granule surface characteristics.  
           [0003]    Granular products include powders as well as coarser mixtures of granules. Examples of granular products that may be inspected include pharmaceutical products, food products (rice, grain, cereals, flour, confections, sugar, etc.), cosmetic products, aggregates, ores, plastics and other petrochemical products, and many more.  
           [0004]    Various methods and devices for performing such an analysis have been employed for these purposes which may employ laser diffraction, spectroscopy, and various forms of visual image analysis.  
           [0005]    A problem in inspecting granular products, particularly when image analysis is employed, is in presenting the product to the image capturing device so as obtain an optimal image of the product. It is desired, for example, to have a controllable quantity of the product within the image area so that an image can be made of the desired quantity. In addition, it is desired to have a controlled and uniform spread of the material so that the image represents a fair sampling of the product. It is also desirable to be able to control a thickness of the spread of material in the image area, depending on what type of characteristics are being determined. In some cases a single layer of granules is required to achieve imaging of substantially all of the product, for example, if it is necessary to show the complete absence of a particular defect. In other cases, it may be desired to have less than a single layer, i.e., with space between the individual granules for improved inspection of individual granule characteristics. In still other cases, a thicker layer of granules may be desired when a sampling of the product characteristics is sufficient. It is also desired to present the granules to an image capturing device in an even manner, so that the granules being imaged are on a single plane and/or at a given distance from the imaging device.  
         BRIEF SUMMARY OF THE INVENTION  
         [0006]    An object of the present invention is to provide an inspection device and method for inspecting a granular product that is capable of presenting a quantity of the granular product in an image area in a controlled manner.  
           [0007]    An alternate or additional object of the present invention is to provide a device for presenting a sample of the granular product to an image area having a controlled thickness that may include a single layer of particles or multiple layers of particles. A further alternate or additional object is to provide a device that enables specific inspection conditions to be easily repeatable for subsequent inspections.  
           [0008]    The present invention provides an inspection device for inspecting a granular product that includes a feed tray having a receiving region for receiving the granular product and an imaging region and a vibration device configured to impart vibrations to the feed tray for moving granules of the granular product from the receiving region to the imaging region. The inspection device also includes an image capturing device configured to capture an image of a sample of the granular product in an image area of the imaging region.  
           [0009]    The present invention also provides a method for inspecting a granular product that includes disposing the granular product on a receiving region of a feed tray, vibrating the feed tray so as to induce a movement of the granular product from the receiving region of the feed tray to an imaging region of the feed tray, and capturing an image of a sample of the granular product in an image area of the imaging region. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    Several embodiments of the present invention are elaborated upon below with reference to the accompanying drawings, in which:  
         [0011]    [0011]FIG. 1 shows a perspective view of one embodiment of an inspection device according to the present invention;  
         [0012]    [0012]FIG. 2 shows a close-up view of a portion of the inspection device in FIG. 1;  
         [0013]    [0013]FIG. 3 shows a partial view of an alternative embodiment of an inspection device according to the present invention;  
         [0014]    [0014]FIG. 4 shows a partial schematic representation of an inspection device according to the present invention having a scale; and  
         [0015]    [0015]FIG. 5 shows a partial schematic representation of an inspection device having a cover for the feed tray. 
     
    
     DETAILED DESCRIPTION  
       [0016]    [0016]FIGS. 1 and 2 show one embodiment of an inspection device  10  according to the present invention. A granular product may be poured into the entry spout  11  of the device, which guides the granular product through an entry shaft  12  to a receiving region  20  of an elongated feed tray  13 , which is disposed substantially horizontally inside a housing  14  of the device  10 . A gap  15  between an upper surface of the feed tray  13  and a lower end of the entry shaft allows the granular product to spread onto the feed tray  13 . The size of the gap  15  may be adjustable (such as by rotating the entry shaft  12  on threads  16  so as to raise and lower the entry shaft with respect to the feed tray  13 ). Adjusting the gap  15  provides one way to control the amount of granular material which may move along the feed tray  13 .  
         [0017]    The feed tray  13 , in this embodiment, is supported on its lower end by two struts  17  that extend upward from a vibrating device  18 , which may include a vibrating motor inside of a motor housing. A bracket  19  may be interposed between the struts  17  and the feed tray  13  to form the connection.  
         [0018]    When the vibrating device  18  is switched on, vibrations from the vibrating motor are imparted to the feed tray  13  through the struts  17  and bracket  19 . Preferably, the elongated feed tray  13  vibrates back and forth in a longitudinal direction, or at least the movements include components in the longitudinal direction (i.e. in a direction parallel to the central axis  26 ) of the feed tray  13 . In the embodiment shown in FIG. 1, the supporting struts  17  are both angled to the right. The vibrations imparted to the feed tray  13 , cause a movement of the granules of the granular product on the feed tray in a general direction from the receiving region  20  to the imaging region  21  of the feed tray (i.e., in a right to left direction with respect to FIG. 1). The amplitude and frequency of the vibrating motor may be adjusted to increase or decrease the rate and other characteristics of the movement of the granules along the feed tray  13 .  
         [0019]    As the granules migrate from the receiving region  20  of the feed tray  13 , they encounter a gate mechanism  22  disposed between the receiving region  20  of the feed tray and an intermediate region  28  of the feed tray. The gate mechanism includes gate posts  23  and a gate panel  24  having an orifice  25 . The gate mechanism  22  allows only a controlled quantity of the granular product to pass through the orifice  25 , while keeping the rest of the granular product in the receiving region  20 . The gate posts  23  allow easy removal of the gate panel  24  and replacement with another gate panel having a different sized orifice or a different number of orifices. The gate panel orifice  25  shown in FIG. 1 is centered with respect to a width of the elongated feed tray  13 , and thus has the additional effect of focusing the flow of granules toward the central axis  26  of the feed tray  13 . An access door  27  is provided in the top of the housing to provide access to an operator of the inspection device, to change the gate panel  24  in the gate mechanism  22  or to otherwise access the components or product granules inside the inspection device  10 .  
         [0020]    After passing through the orifice  25  of the gate mechanism  22 , the granules enter an intermediate region  28  of the feed tray. As the granules migrate through the intermediate region  28 , the vibrations will tend to disperse the stream of granules out from the central axis  26  of the feed tray  13  and toward the side walls  29 . Two deflectors  30 , one protruding from each side wall of the feed tray, separate the intermediate region  28  from the imaging region  21  of the feed tray. The deflectors  30  focus the flow of granular product away from the walls  29  and toward the central axis  26  of the tray  13 , as the granular product enters the imaging region  21  of the tray. Focusing the flow towards the central axis  26  reduces the amount of contact of the granular material with the side walls  29  in the imaging region  21  of the tray which may interfere with the flow and have undesirable effects on the image. Deflectors  30  may have various sizes and orientations relative to the wall of the tray as is optimal for providing product flow past the camera  34 . Deflectors  30  may be adjustable (in size and/or orientation), or may be replaceable with deflectors of a different size and/or orientation. By controlling the flow with a fixed orifice  25  in gate mechanism  22 , and fixed size and orientation of the deflectors  30 , together with a fixed and repeatable vibration speed of vibrating device  18 , the inspection device can image substantially the same amount of sample from analysis to analysis of the same substance which is important for obtaining meaningful and repeatable results for process control.  
         [0021]    A tapping mechanism  31  is disposed underneath the intermediate region  28  of the feed tray  13 . The tapping mechanism may include a solenoid or other known devices for activating a hammer element  32  for tapping the bottom surface of the feed tray. The tapping mechanism  31  may be disposed at other appropriate locations along the feed tray  13 . The tapping mechanism can be activated to tap the feed tray  13  to dislodge one or more granules that may get stuck along the way from the receiving region to the imaging region or within either region. Granules may tend to stick to the floor or side walls  29  of the tray  13 , or to the gate mechanism  22  or deflectors  30  due to the presence of static electricity, for example, or humidity or wetness of the granules or components.  
         [0022]    A camera tower  33  is disposed on an upper side of the housing  14  which includes an image capturing device, which may be a camera  34 . In general, a CCD imaging device can be used as the image capturing device. Other forms of detectors could also be used, including IR sensing devices and UV sensing devices, such as in cases in which chemical or temperature related wavelength emissions from the product can best be sensed by non visible detectors. In this embodiment, the camera  34  is disposed vertically with a lens pointing downwards toward an image area  35  of the imaging region  21  of the feed tray  13 . The camera  34  may be connected to a microprocessor for performing image analysis on the images captured by the camera  34 . A display device may also be provided for visual inspection of the granules by the device operator or other persons. The microprocessor preferably includes software for performing various analyses on the image, so as to determine characteristics of the granules being sampled, such as color and size characteristics of the granules, and to qualify and quantify characteristics of defects or foreign particles within the sample.  
         [0023]    The same or a different microprocessor may be operationally connected to other components in the device such as the vibrating device  18 , tapping mechanism  31 , gate mechanism  22  and/or the illumination device  36 , to provide user-friendly control options to these devices. Thus, the operator is preferably able to control the amplitude and/or frequency of the vibrating device  18  and the characteristics of the illumination of the sample, and to activate the tapping device  31 , so as to provide optimal conditions for inspection of a particular sample depending on the granular product being inspected and the inspection characteristics being determined. The components are preferably controlled so as to facilitate replication of particular conditions for subsequent inspection operations.  
         [0024]    The inspection device may include an illumination source, such as, in this embodiment, a ring light  36  that is disposed between the camera lens and the image area  35  on the tray  13 . The ring light  36  is useful for providing light on all sides of the granules being imaged for improved imaging of the granules. A voltage regulator is preferably provided, in operational connection with the light source  36 , so as to be able to control the intensity of light and to repeat particular lighting conditions in subsequent inspection operations. The color of the illumination provided by the light source may also be adjustable. A color of the tray  13 , particularly a color of the tray surface within the image area  35 , may be selected so as to provide good contrast with the defect and/or granules being imaged. For example, if the inspection device is being used to determine quantities of black speck within a sample, a color could be chosen that is close to the color of the normal product in the sample. If the inspection device is being used to determine particle size of the granular product, a color may be chosen to contrast with the color of the product. For a combined analysis of particle size and defect detection, the color may be chosen so as to provide contrast to both the good product particles and the defective ones.  
         [0025]    After passing through the imaging region  21  of the tray, the granules reach the tray edge  37  and drop off into a catch bowl  38 . A second access door  39  is provided in the inspection device  10  to remove the sampled product from the device. Alternatively, the inspection device  10  could be incorporated in-line to a production process for a granular product so that the granular product flows from an earlier production phase into the entry spout  12 . Instead of the catch bowl  38 , the granular product could move from the imaging region  22  of the tray  13  to a subsequent processing stage, such as by falling off the tray edge  37  into a funnel that is connected to the subsequent processing stage.  
         [0026]    The alternative embodiment of the inspection device  50  shown in FIG. 3 offers a more compact design. Instead of being mounted vertically in a camera tower on top of the device, the image capturing device  34   a  in this embodiment is mounted horizontally within the housing (or, alternatively, on a side of the housing). Two prisms  51  are disposed to provide a view of the granules in the image area  35  to the image capturing device  34   a . The feed tray  13   a  in shown in FIG. 3 includes higher side walls  29   a  which may be helpful for containing fine particles that become more easily airborne, and/or when using a high amplitude vibrations. Feed trays in this or other embodiments may have different shapes and sizes that may be used to suit the inspection requirements and the properties of the granular product being inspected. The ring light  35  is shown to be mounted to a post  52  and may be adjusted vertically for optimal illumination of a particular sample of granular product. The position of the lens of the camera  34   a  is, of course, also adjustable for optimizing the image. A funnel  53  is shown, which may be disposed over the entry spout in this or other embodiments to provide easier input of product into the entry spout.  
         [0027]    A second image capturing device  54  may also be disposed on this or another embodiment so as to capture images of granules as they fall off of the edge of the feed tray through a second image area  55 . The second image capturing device  54  may be used to obtain additional information about the granules such as size and shape information where product features and/or processing conditions are not optimal for extracting all information from the granules in the image area  35  of the feed tray. The second image capturing device  54  would preferably be accompanied by a second illumination source appropriately mounted so as to provide illumination of the particles in free fall. It may be connected to the same or a different microprocessor as the first image capturing device  34   a  for analysis of the image.  
         [0028]    [0028]FIG. 4 shows a schematic representation of an inspection device  70  including a scale  71  beneath the catch bowl  72 . As the granules fall off the edge of the feed tray  13   c  into the catch bowl  72 , the scale  71  detects the change in weight. Preferably, scale  71  is also connected to the same or a different microprocessor as the first image capturing device  34   a  or  34 , so that the change in weight per unit time can be calculated and used together with the additional data being obtained by the inspection device. The detection of the change in weight is useful in many instances due to variations in the flow of the product. For example, when a dry particulate mixture in a container is emptied out through a chute or bottom opening in the container, there is a tendency for smaller particles to filter out first, leaving the last part of a batch with a greater percentage of larger particles. Given this tendency, the flow measured as weight per unit time will vary from the beginning of the batch to the end. Being able to inspect the granules per unit weight allows the operator to run a partial batch of a product and get meaningful results. This feature likewise accounts for variations in the speed of the flow which may be different at the start of the run than at the end.  
         [0029]    In an advantageous embodiment, shown in FIG. 5, the inspection device may include a tray cover element  81 , which covers the feed tray  13  so as to prevent airborne dust particles from the granular product from escaping the area of the feed tray. A chute element  82  may also be provided, which surrounds an area through which the particles fall from the edge  37  of the feed tray  13  into the catch bowl  38 . Preferably, catch bowl cover  83  is also provided to keep airborne dust particles from escaping the catch bowl  38 . Elements  81 ,  82 , and  83  may be connected as a single element or may be separate elements that are operatively connected to one another. Particularly when inspecting a granular product that includes fine dust particles, it is advantageous to cover the entire path of the granular product from entry spout  11  to catch bowl  38 . An excess of dust particles may cause undesired effects, such as, for example, harm to sensitive electronic components.  
         [0030]    It will of course be understood that the present invention has been described above only by way of example and that modifications of details can be made within the scope of the invention.