Abstract:
The single-camera angled conveyance inspection method and apparatus includes upwardly and downwardly angled conveyance mechanisms positioned within an instantaneous field of view of a digital line scan camera. As a rotating object is moved over the conveyances by a helical guide, the camera obtains images of the object and communicates the images to a processor. The processor assembles a reflectance and fluorescence image of the object including detected defects and/or contamination on the outer surface of the object.

Description:
FIELD OF THE INVENTION 
     The disclosed method and apparatus relates to imaging a whole surface of a rotating object. Specifically, the method and apparatus relates to imaging a whole surface of a spheroidal rotating object using an angled conveyance system. 
     BACKGROUND OF THE INVENTION 
     Currently, the most common method for inspecting essentially spherical objects (such as fruits and vegetables) requires production line personnel to visually inspect the objects as the objects are conveyed along a production line. However, the human visual inspection process is both slow and unreliable, and some contaminating materials that pose serious health risks are hard to visually identify—particularly on a moving production line. Further, inspectors do not systematically rotate each individual object so that all surfaces of the inspected object are visible to the inspector. 
     To address these vulnerabilities, fruit and vegetable processors are developing machine vision systems to identify defects and contaminants. One example of such a system is disclosed in U.S. Pat. No. 7,787,111 to Kim et al. (hereinafter “Kim”), which is hereby incorporated by reference. The system disclosed by Kim comprises a rapid online line-scan imaging system capable of both hyperspectral/multispectral reflectance and fluorescence imaging. Reflectance imaging at multiple wavelengths detects quality and surface anomalies, while fluorescence imaging at multiple wavelengths is used to detect fecal matter and other types of bacterial contamination. 
     Although these examination tools and techniques improve the inspection process, the imaging systems are complex and expensive. For example, in accordance with Kim, multiple cameras may be required to adequately inspect all surfaces of a spheroid. Further, the data collected from all cameras must be processed and synchronized to accurately portray the three-dimensional spheroidal object. For maximum efficiency and minimal error, synchronization and processing should occur almost immediately to ensure that defective objects are not comingled with non-defective items. 
     The method and apparatus described herein simplifies the imaging process by providing an imaging system that utilises only one camera and associated processor. The system quickly and effectively gathers the imaging data for the whole surface of an inspected object and allows for the identification of essentially all surface defects as well as selected types of bacterial (fecal) contamination. 
     SUMMARY OF THE INVENTION 
     This disclosure is directed to a method and apparatus for inspecting objects, preferably spheroidal fruits and vegetables traveling along a conveyor line. In accordance with the method and apparatus, a rotating object is directed down a downwardly-angled conveyance and up an upwardly-angled conveyance. The downwardly and upwardly angled conveyances comprise a plurality of members that rotate the object as the object moves over the conveyances. A helical guide(s) encircles each of the members so that the helical guides direct the object forward along the conveyances. A digital line scan camera is positioned so that as the object moves over the conveyances, the object moves through the instantaneous field of view (IFOV) of the camera. The camera communicates images of the object to a processor. The processor receives the images and produces image data for the object. The inspection system is structured so that the object is retained or rejected based on the image data produced by the processor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an elevational view of the single-camera angled conveyance inspection system. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     As generally shown in  FIG. 1 , the method and apparatus described herein comprises an inspection system  10  that includes a downwardly angled conveyance mechanism  12  and a corresponding upwardly angled conveyance mechanism  14 . As a rotating object  20  moves in the direction of travel indicated by the arrow  16 , the object  20  moves into the IFOV (as defined by the area  18 ) of a digital line scan camera  30 . The processor  40  communicating with the camera  30  collects and processes a line scan images of the object  20  to determine whether the object  20  should be rejected or retained for further processing. 
     As best shown in  FIG. 1 , in the preferred embodiment, the downwardly angled conveyance  12  is comprised of first  22  and second  24  downwardly angled elongated members, and the upwardly angled conveyance  14  is comprised of essentially identical first  26  and second  28  upwardly angled elongated members. The downwardly angled  12  and upwardly angled  14  conveyance mechanisms are essentially mirror images of one another. 
     The downwardly angled conveyance  12  in combination with the upwardly angled conveyance  14  forms a “V” shape. The exact angle of the downward  12  and upward  14  conveyances relative to each other (and to horizontal) may be varied as required to achieve the best results for a specific application. The angular travel of the objects  20  along the conveyances  12 ,  14  (relative to the IFOV  18  of the camera  30 ) functions to expose surfaces of the object  20  that would not otherwise be visible to a conventionally-positioned overhead camera on a traditional horizontal conveyor. The increased surface area exposure enables the system  10  to more thoroughly inspect the outer surface of the objects  20  and thereby detect defects and contamination that might otherwise go undetected. 
     The elongated members  22 ,  24 ,  26 ,  28 , may be smooth or textured, as required. As best shown by the arrows  21 , the members  22 ,  24 ,  26 ,  28  rotate in the same direction so that the inspected object  20  is continuously rotated as it moves down the downwardly angled conveyance  12  and up the upwardly angled conveyance  14 . The members  22 ,  24 ,  26 ,  28  include helical guides  32 ,  34 ,  36 ,  38  that encircle the respective members  22 ,  24 ,  26 ,  28  and guide the inspected objects  20  forward through the inspection system  10 . In the preferred embodiment, the inspected object  20  is a spheroidal food product, such as a fruit or vegetable. 
     Although not specifically shown in the drawings, the inspection system  10  includes a lighting system that illuminates the rotating object  20 , as disclosed (for example) in Kim. Specifically, the lighting system may include a quartz-tungsten halogen (QTH) reflectance lamp. Near infrared (NIR) light emitting diodes (LEDs) or an NIR laser with (or without) a long pass filter can also be used as a reflectance lamp. The lighting system may also include a micro discharge lamp (MDL)-high intensity ultraviolet light. LEDs, a laser, or a pressurized vapor lamp can be used for fluorescence excitation. The system may further include long pass filters and a variety of other lighting and camera accessory equipment, as required to elicit reflectance, fluorescence, or other illumination-related responses useful in detecting defects and/or contamination on the inspected object  20 . 
     In operation, the position of the camera  30  IFOV (as defined by the area  18 ) is coordinated with the rotation of the object  20  and the placement of the helical guides  32 ,  34 ,  36 ,  38  so that the IFOV captures a selected number of rotations of the object  20 , as the object  20  travels along the conveyances  12 ,  14  and is illuminated by (at least) the fluorescent and reflectance lighting systems. 
     In the preferred embodiment, the processor  40  receives image data from the camera  30  and assembles a concatenated line scan image of each inspected object  20 . Processor  40  software automatically edits the assembled image data so that the data essentially comprises an “image cube” depicting all outer surfaces of the object  20 , as the object  20  moves through the inspection system  10 . The image cube data is then scrutinized based on pre-determined contamination and defect standards (expressed as contamination/defect thresholds). Examined objects  20  that are determined to meet the standards are retained for further processing, and objects  20  that are substandard are rejected. 
     In an alternative embodiment, the components of the inspection system  10  are essentially the same, however the relative positions of the downward  12  and upward  14  conveyances may be reversed. In this alternative embodiment, the upward conveyance  14  precedes the downward conveyance  12  in the tandem arrangement disclosed in the preferred embodiment. In this configuration, conveyances  12 ,  14  form an inverted “V”, which may be advantageous in some inspection applications. 
     For the foregoing reasons, it is clear that the method and apparatus described herein provides an innovative system for inspecting three-dimensional objects, preferably spheroidal objects on a conveyance line. The system may be modified in multiple ways and applied in various technological applications. For example, although the method and apparatus described herein is generally directed to spheroidal food products, in alternative embodiments, the device may have some application to the inspection of non-spheroidal food or non-food items (such as manufactured products). 
     The method and apparatus described herein may be modified and customized as required by a specific operation or application, and the individual components may be modified and defined, as required, to achieve the desired result. 
     Although the materials of construction are not described, they may include a variety of compositions consistent with the function described herein. Such variations are not to be regarded as a departure from this disclosure&#39;s spirit and scope, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.