Abstract:
Apparatus and method for slicing a food product having a non-uniform cross-sectional area. A laser line scanner scans the cut face of the food product. A line scan camera receives light reflected from the cut face of the food product. The line scan camera is positioned such that the line field of view of the line scan camera intersects the scanning line of the laser line scanner at the cut face of the food product. A controller determines an area of the cut face of the food product using the light reflected from the cut face of the food product and advances the food product to be cut by the cutting device by an amount such that a next slice of the food product cut by the cutting device will have a thickness such that the next slice will be of the predetermined weight based upon the area of the cut face.

Description:
TECHNICAL FIELD  
         [0001]    The present invention relates generally to apparatus and methods for slicing food products and, more particularly, to apparatus and methods for slicing food products with an adjustable cutting thickness determination obtained through optical means.  
         BACKGROUND  
         [0002]    In the food industry, it is common to pre-cut various food products, such as meats, before the food products are dispensed to the consumer. As an example, pork chops are commonly cut from a pork loin and marketed to the consumer individually or in packages with a plurality of pork chops in each package.  
           [0003]    Various automated systems have been constructed to perform the task of pre-cutting food products, such as meats, to create individual items for the convenience of the consumer. For example, an apparatus could cut pork chops having a consistent thickness resulting in multiple pork chops having a constant thickness.  
           [0004]    However, some food products, including pork loins, have a non-uniform cross-sectional area. The shape of a pork loin is not uniform over its length. A pork loin can be bigger or smaller at one end or the other and may vary in cross-sectional area along its length. As progressive cuts made in the pork loin, the cross-sectional area of the pork loin may vary. Thus, successive pork chops cut from a pork loin may be larger or smaller depending upon the actual cross-section of the pork loin where the pork chop is cut. Thus, cutting a plurality of items (e.g., pork chops) from a food product (e.g., a pork loin) with a constant thickness may result in successive pork chops which can vary significantly in weight.  
           [0005]    Food products may be sold by weight. Thus, if the weight of individual pork chops vary, the collective of weight of a package of pork chops may also vary. However, since the package of pork chops is being sold to the consumer by weight, different packages of pork chops (all containing the same number of pork chops) may have different prices. The consumer may then need to select accordingly and purchase a package of pork chops reasonably matching the consumer&#39;s expectations.  
           [0006]    Food products may also be sold by number of items. For example, a package of pork chops may be sold as a package containing a predetermined number of pork chops irrespective of the weight of an individual pork chop. Since the weight of individual pork chops may vary, the weight of a package of a predetermined number of pork chops will also vary. This may result in the consumer getting more or less (weight) depending upon which package is purchased. Thus, differing packages may be more or less desirable for the consumer to purchase.  
           [0007]    However, food products may also be sold requiring a precise number of items and a precise weight for those items, either collectively or individually. This dual requirement will not allow a significant variation in weights among the individual items.  
           [0008]    Since the cross-section of a food product, e.g., a pork loin, may vary but the weight of each individual item, e.g., pork chop, must stay the same, then the thickness of each individual item must either vary or another operation must be accomplished following the cutting in order to adjust the weight of each individual item. For example, trimming of the edges of a cut pork chop may be done in order to reduce the weight of each pork chop to be consistent among pork chops. However, not only is manual trimming time-consuming but it also results in a significant amount of wasted material.  
           [0009]    Prior art optical systems have been employed to attempt to determine the size of a product being cut and to adjust the thickness of the cut in order to control the weight of each individual item being cut.  
           [0010]    U.S. Pat. No. 5,267,168, Antonissen et al, Apparatus For and Method of Controlling Slicing Machine, discloses a slicing machine which includes a control system having a camera which views a cut face of a product being sliced. The processing of the image data includes classifying the image data by comparison with an intensity threshold which is varied automatically in accordance with the populations of data and the different classes. A source of illumination ( 7 ) is positioned below the face of the product ( 3 ) being cut by blade ( 1 ). A camera ( 6 ) is also set at an angle with respect to the face of the product ( 3 ) being cut by blade ( 1 ). The source of illumination ( 7 ) illuminates the entire face of the product ( 3 ) being cut at one time and the camera ( 6 ) senses light from a general area facing the product ( 3 ) being cut which includes light from the source of illumination ( 7 ) being reflected.  
           [0011]    U.S. Pat. No. 5,054,345, Weber, Method of Obtaining Constant Weight Portions or Slices of Sliced Food Products, discloses a method for obtaining constant weight portions or slices from sliced food products where, in each case, individual slices or portions of several slices with exactly predeterminable weight can be formed in real time operation during the cutting process by detecting the cut surface area, taking account of the specific weight and computing of the required feed of the product. A light source ( 52 ) is set at an angle α with respect to surface ( 48 ) of ham ( 10 ). The light ( 54 ) remitted or diffusely reflected from surface ( 48 ) falls as light beam ( 54 ) onto video recorder ( 56 ) arranged at an angular specular reflection angle β also with respect to surface ( 48 ) of ham ( 10 ). Again, the light source ( 52 ) illuminates the entire surface ( 48 ) of the ham ( 10 ) and the video recorder ( 56 ) records light including light being reflected from surface ( 48 ) of ham ( 10 ).  
           [0012]    A problem with optical systems intended to determine the cross-sectional area of the food product to be cut is that it is difficult for the sensor to determine what light is reflected from the food product and what light is ambient or is reflected from background clutter. Some systems use an amplitude threshold to filter the incoming light signals. However, ambient light or light reflecting from the background may still be of sufficient amplitude to interfere with a proper determination of the cross-sectional area of the cut face of the food product.  
         SUMMARY OF THE INVENTION  
         [0013]    Thus, there is a need for an accurate system to cut a plurality of slices of the food product, which has a variable cross-sectional area, with the slices having accurate predetermined weights. Such a system would allow the packaging of the plurality of slices of the food product in which the number of slices is constant and in which the weight of the package is constant.  
           [0014]    The present invention solves many of the problems associated with prior art optical systems intended to determine the cross-sectional area of a food product so that the food product may be sliced at an appropriate thickness.  
           [0015]    Common prior art optical systems designed to perform this task have a sensor, e.g., a camera, which views the entire face of the food product being cut.  
           [0016]    Commonly, prior art optical system designed to perform this task flood the entire cut face of the food product being sliced with illumination. Such systems commonly view the area, including the cut face of the food product, with a camera or video recorder expecting to capture the light from the illumination source which is reflected from the cut face of the food product with the camera or video recorder and thereby determine the cross-sectional area of the cut face. However, extraneous ambient light and, especially, light from the illumination source which reflects off of a surface other than the cut face of the food product often interferes with making a quick and accurate determination of the area of the cut face. The job of the pusher or gripper is to hold the food product securely in place throughout the slicing operation. However, light from the illumination source may reflect from the pusher or gripper (as well as other components) and also be received by the camera or video recorder. The result may be a determination that the cross-sectional area of the food product being sliced is larger than it really is and the resulting next slice of the food product being inappropriately thin and the weight of the slice being inappropriately light. This problem is exacerbated as the slicing operation of the food product nears completion and the pusher or gripper is necessarily brought very close to the cut face being examined, because of the resulting shortness in the already mostly sliced food product. In one implementation, the pusher or gripper is actually constructed of bright and shiny stainless steel, in order to maintain cleanliness of the equipment, making reflections from its surface even more likely.  
           [0017]    The present invention avoids these problems, in part, by scanning the cut face of the food product with a laser line scanner illuminating not the entire cut face of the food product and adjacent areas but only a narrow line of illumination. The laser line scanner illuminates the food product as the food product is being moved with respect to the illumination of the laser line scanner resulting in the entire cut face of the food product being illuminated over a period of time as the relative position of the food product and the laser line scanner changes. A complementary line scan camera is positioned so that its line field of view intersects the line illumination from the laser line scanner at the cut face of the product during the scanning operation. Since the line view of the line scan camera and the line illumination of the laser line scanner only intersect along the scanning plane at the cut face of the food product, only light reflected from the cut face of the food product will be received by the line scan camera and only light reflected from the cut face will be used in a determination of the area of the cut face of the food product. For each line illumination, the line scan camera can accurately determine the length of the line being reflected and the dimension, e.g., height, of the cut face of the food product at that point across the entire cut face of the food product. As the food product and the laser line scanner are moved with respect to each other, successive line illumination scans are captured by the line scan camera and successive determinations are made to the dimension of the cut face of the food product at that point. Knowing the width of each line scan illumination and the distance between successive line scans, allows these dimensions to be summed in order to accurately determine the cross-sectional area of the cut face of the food product. Once the cross-sectional area is known, the known density of the food product will allow the food product to be sliced at an appropriate thickness so that each slice can have a predetermined weight.  
           [0018]    In one embodiment, the present invention provides an apparatus for slicing a food product, having a non-uniform cross-sectional area along a longitudinal axis, capable of being sliced along a cutting line orthogonal to the longitudinal axis to obtain a plurality of slices of the food product having a predetermined weight. A cutting device is positioned along the cutting line. A cutting table is capable of moving the food product along the longitudinal axis and along an axis parallel to the cutting line. A laser line scanner is capable of scanning the cut face of the food product with a scanning line along an orientation as the food product is moved orthogonal to the longitudinal axis. A line scan camera is capable of receiving light reflected from the cut face of the food product. The orientation of the laser line scanner matches the orientation of the line scan camera. The line scan camera is positioned such that the line field of view of the line scan camera intersects the scanning line of the laser line scanner at the cut face of the food product. A controller determines an area of the cut face of the food product using the light reflected from the cut face of the food product and advances the food product to be cut by the cutting device by an amount such that a next slice of the food product cut by the cutting device will have a thickness such that the next slice will be of the predetermined weight based upon the area of the cut face.  
           [0019]    In an alternative embodiment, the present invention provides a method of adjusting a cutting width of a food product, having a non-uniform cross-sectional area along a longitudinal axis, capable of being sliced along a cutting line orthogonal to the longitudinal axis to obtain a plurality of slices of the food product having a predetermined weight. The food product is moved along a scanning axis parallel to the cutting line. The cut face of the food product is scanned with a scanning line along an orientation from a laser line scanner as the food product is moved along the axis. Light reflected by the cut face of the food product is received with a line scan camera having a line field of view along an orientation. The orientation of the laser line scanner matches the orientation of the line scan camera. The line scan camera is positioned such that the line field of view of the line scan camera intersects the scanning line of the laser line scanner at the cut face of the food product. An area of the cut face of the food product is determined using the light reflected from the cut face of the food product. The food product to be cut is advanced by the cutting device by an amount such that a next slice of the food product cut by the cutting device and will have a thickness such that the next slice will be of the predetermined weight based upon the area of the cut face. The food product is cut with the cutting device.  
           [0020]    In a preferred embodiment, the cutting table repeatedly moves the food product in a direction parallel to the cutting line allowing the food product to be sliced by the cutting device and subsequently moves the food product in a reverse direction away from the cutting device.  
           [0021]    In a preferred embodiment, the laser line scanner scans the cut face of the food product while the cutting table is moving the food product in the reverse direction away from the cutting device.  
           [0022]    In a preferred embodiment, the controller determines the area of the cut face of the food product from measurements taken while the cutting table is moving the food product in the reverse direction away from the cutting device.  
           [0023]    In a preferred embodiment, the area of the cut face of the food product is based upon an amplitude threshold of the light reflected by the cut face of the food product.  
           [0024]    In a preferred embodiment, the food product has a density which varies, the density being visually identifiable and wherein the predetermined weight is also based upon the density of the food product.  
           [0025]    In a preferred embodiment, the orientation of the laser line scanner and the orientation of the line scan camera is orthogonal to the cutting line.  
           [0026]    In a preferred embodiment, the laser line scanner is positioned at an acute angle to the longitudinal axis.  
           [0027]    In a preferred embodiment, the line scan camera is positioned with the line field of view parallel to the longitudinal axis. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0028]    [0028]FIG. 1 is a top plan schematic view of an embodiment of the apparatus of the present invention;  
         [0029]    [0029]FIG. 2 is a diagram illustrating the line scan camera view of a series of line scans made across the cut face of a food product made by the laser line scanner of the apparatus illustrated in FIG. 1; %  
         [0030]    [0030]FIG. 3 is a flow chart illustrating the operation of an embodiment of the present invention;  
         [0031]    [0031]FIG. 4 is a top plan schematic view of an embodiment of the apparatus of the present invention illustrating the effect of located behind the scanning plane; and  
         [0032]    [0032]FIG. 5 is a top plan schematic view of an embodiment of the apparatus of the present invention illustrating the effect of located in front of the scanning plane. 
     
    
     DETAILED DESCRIPTION  
       [0033]    [0033]FIG. 1 shows, in schematic format, an apparatus  10  for slicing food product  12 . Food product  12 , in this example, is a pork loin supported by food table  14  secured by pusher  16 . Cut face  18  of food product  12  faces to the right in the drawing. Cutting blade  20  is positioned along cutting plane  22  and is adapted to cut a slice, in this example, a pork chop, from food product  12 .  
         [0034]    Food table  14  can move forward along a longitudinal axis  24  of food product  12 , toward cutting plane  22  and to the right in the drawing, in order to advance cut face  18  of food product  12  into the proper position so that the proper amount of food product  12  can be sliced from a food product  12  by cutting blade  20 . Food table  14  can also move backward along longitudinal axis  24  of food product  12 , away from cutting plane  22  and to the left in the drawing, either to enable cut face  18  of food product  12  to be scanned or to facilitate cut face  18  of food product  12  to be able to clear cutting blade  20  upon completion of a slicing operation. In addition, food table  14  can also move sideways orthogonal to longitudinal axis  24  of food product  12 , upwards and downwards in the drawing, in order to engage or disengage food product  12  with cutting blade  20 .  
         [0035]    In general, apparatus  10  operates with food table  14  moving food product  12 , in this embodiment a pork loin, forward along longitudinal axis  24  of food product  12  toward cutting plane  22  in order to position food product  12  for an appropriate cutting thickness. Once appropriately positioned, food table  14  moves food product  12  upwards in the drawing into cutting blade  20  cutting a slice from food product  12 . Optionally, food table  14  moves backwards (to the left in the drawing) away from cutting plane  22  and order to clear cutting debris and to ensure that food product  12  will be clear of cutting blade  20 . Food table  14  then moves food product  12  downwards in the drawing away from cutting blade  20 . Food table  14  is then ready to begin another cycle by advancing food product  12  forward again toward cutting plane  22  so that food product  12  is properly positioned so that another slice may be cut from food product  12 .  
         [0036]    As food table  14  moves food product  12  downwards in the drawing, laser line scanner  28  scans a line across cut face  18  of food product  12 . Laser line scanner  28  is positioned at an acute angle  30  to longitudinal axis  24 . Even though laser line scanner  28  is stationary, laser line scanner  28  scans a vertical line successively across cut face  18  of food product  12  as food table  14  moves of food product  12  downwards in the drawing (to the left from laser line scanner&#39;s  28  view) because cut face  18  of food product  12  is moving.  
         [0037]    At the same time, line scan camera  32  is positioned with a field of view oriented to intersect line scan  34  from laser line scanner  28  at cut face  18  of food product  12  along scanning plane  36 . Light  26  reflected from cut face  18  of food product  12  is within the line field of view of and will be captured by line scan camera  32 . Again as food product  12  moves across the field of view of line scan camera  32 , the entire cut face  18  of food product  12  will be scanned. The result of line scans  36  are passed to controller  42 .  
         [0038]    [0038]FIG. 2 illustrates a series of line scans  36  received by line scan camera  32 . In the orientation illustrated in FIG. 1, scanning will sequentially occur starting with scan line  36  on the left in FIG. 2, since the left side of cut face  18  of food product  12  is the first portion of food product  12  viewed by line scan camera  32  as food product  12  is moved across the line field of view of line scan camera  32 . Since laser line scanner  28  scans in a vertical line at a rate much higher than the horizontal velocity of food table  14 , line scans  36  are still substantially a vertical even though food table  14  is moved horizontally. Of course, the same result is obtained even though line scans  36  are not perfectly vertical. For purposes of illustrating and describing the invention, line scans  36  are illustrated as being vertical. Subsequent line scans  36  will progressively move across cut face  18  of food product  12  until the entire cut face  18  of food product  12  has been scanned.  
         [0039]    Line scan camera  32  will only receive light reflected from cut face  18  of food product  12 . Thus, each of line scans  36  received by line scan camera  32  represents the height of cut face  18  of food product  12  at the horizontal location of a particular one of line scans  36  across cut face  18  of food product  12 . If cut face  18  of food product  12  is higher, line scan  36  received by line scan camera  32  will be relatively longer. If cut face  18  of food product  12  is lower, line scan  36  received by line scan camera  32  will be relatively shorter.  
         [0040]    Once cut face  18  of food product  12  has entirely passed the field of view of line scan camera  32 , line scan camera  32  will have captured a series of line scans  36 , each having a length representing the height of the cut face  18  of food product  12  at the horizontal point along cut face  18  of food product  12  where the laser line scan  34  from laser line scanner  28  intersects scanning plane  38 .  
         [0041]    Line scan camera  32  is coupled to controller  42  which calculates an area of cut face  18  of food product  12  and subsequently controls food table  14  and order to advance food product  12  into a position so that a slice of food product  12  may be sliced from food product  12  by cutting blade  20 . Knowing the distance between scan lines  36 , based on the speed of the laser line scanner  28  and the speed of food table  14 , enables controller  42  to sum each of line scans  36  and determine the actual area of cut face  18  of food product  12 .  
         [0042]    This process can be described in connection with the flow chart illustrated in FIG. 3. The process starts in block  310 . Block  312  moves food product  12  with respect to laser line scanner  28 . In the preferred embodiment, food product  12  is moved laterally with respect to a direction in which cut face  18  is viewed directly. As laser line scanner  28  is stationary, scanning a vertical line, vertical line scans  36  progressively move across cut face  18 . Of course, it should be recognized and understood that various forms of creating relative movement between food product  12  and laser line scanner  28  are possible. For example, food product may be moved forward or back longitudinally from cutting plane  22 . If laser line scanner  28  is set at an angle to cut face  18 , line scans  36  will also progressively move across cut face  18 . Other geometries and movements are also possible including a stationary food product  12  with a moving laser line scanner  28  or complex movements of food product  12  involving more than one axis.  
         [0043]    As food product  12  is moved relative to laser line scanner  28 , laser line scanner  28  scans cut face  18  of food product  12  (block  314 ) with a vertically oriented laser line scan. At the same time, line scan camera  32  senses light reflected from cut face  18  of food product  12  (block  316 ). Each individual one of laser line scans  36  represents the height of cut face  18  of food product  12  at the horizontal point across cut face  18  which intersects light from laser line scanner  28 .  
         [0044]    Block  318  sums the data from each reflected line scan  36  in controller  42 . Since each of line scans  36  represents the height of cut face  18  of food product  12 , and the distance between each of line scans  36  can be known, the sum of the length of each of line scans  36  times the distance between line scans  36  represents the area of cut face  18  of food product  12 .  
         [0045]    Knowing the area of cut face  18  of food product  12  and the average density of food product  12 , it is an easy calculation to determine a desired thickness which should be sliced from food product  12  in order to obtain a slice having a predetermined thickness (block  320 ).  
         [0046]    Food product  12  is positioned (block  322 ) for cutting a slice of food product  12  having the desired thickness. For example in the preferred embodiment, food table  14  moves forward toward cutting plane  22  so that cutting blade  20  is positioned to slice the appropriate thickness from food product  12 . Food table  14  then moves (block  324 ) food product  12  across cutting blade  20  to cut the desired slice from food product  12 , in the preferred embodiment a pork chop having a desired thickness and weight from a pork loin.  
         [0047]    [0047]FIG. 4 illustrates the effect of the reflection of light from an extraneous object not on, in this case behind, scanning plane  38 . In the apparatus illustrated in FIG. 4, the remaining portion of food product  12  is small. Most of the slices have already been sliced or removed from food product  12 . In this example an extraneous object, namely pusher  16  located at the rear of food product  12  is somewhat near but still located behind scanning plane  38 . Pusher  16  is in a prime position to reflect light from laser line scanner  28  and confuse the result of reflected light incident in the field of view of line scan camera  32  and to provide an erroneous size for the area of cut face  18  of food product  12 .  
         [0048]    Since laser line scanner  28  is positioned at an angle, and this embodiment at an acute angle to the longitudinal axis of food product  12 , an object located behind scanning plane  38  will reflect light from laser line scanner  28  which will be off axis of line scan camera  32 . Light (line scan  34 ) from laser line scanner  28  passes beyond scanning plane  38  and reflects from pusher  16  along line  42  toward line scan camera  32 . However, reflected light  42  is off-axis, below axis in FIG. 4, and out of field of view  44  of line scan camera  32 . Since reflected light  42  is out of the field of view  44  of line scan camera  32 , line scan camera  32  will ignore reflected light  42  and pusher  16  will not affect the scan area of cut face  18  of food product  12 .  
         [0049]    [0049]FIG. 5 illustrates the effect of the reflection of light from an extraneous object positioned in front of scanning plane  38 . Since laser line scanner  28  is positioned at an angle, and this embodiment at an acute angle to the longitudinal axis of food product  12 , an object located behind scanning plane  38  will reflect light from laser line scanner  28  which will also be off axis of line scan camera  32 . Light (line scan  34 ) from laser line scanner  28  does not reach scanning plane  38  before it is reflected along line  46  toward line scan camera  32 . However, reflected light  46  is off-axis, above axis in FIG. 5, and out of field of view  44  of line scan camera  32 . Since reflected light  46  is out of the field of view  44  of line scan camera  32 , line scan camera  32  will ignore reflected light  46  and reflected light  46  will not affect the scan area of cut face  18  of food product  12 .  
         [0050]    It is to be recognized and understood that other geometries between laser line scanner  28 , cut face  18  of food product  12  and line scan camera  32 , beyond those illustrated in the previous Figures, are also contemplated and within the scope of the present invention. It is only necessary that line scans  36  from laser line scanner  28  intersect with the line of field of view of line scan camera  32  at scanning plane  38 . In particular, it is not necessary that line scan camera  32  be located on the longitudinal axis of food product  12 .  
         [0051]    It is also to be recognized and understood that while cutting plane  22  and scanning plane  38  in the preferred embodiment are different planes, it is contemplated that cutting plane  22  and scanning plane  38  could be co-planar. Cutting plane  22  is different from scanning plane  38  in the preferred embodiment so that cut face  18  of food product  12  may be moved back from cutting plane  22  slightly in order to ensure that food product  12  is clear of cutting blade  20  as food product  12  is moved away from cutting blade  20 .  
         [0052]    It is also to be recognized and understood that other possibilities for relative movement between food product  12  and cutting blade  20  are contemplated. For example, food product  12  could remain stationary while cutting blade  20  is moved across food product  12  creating the slicing action.  
         [0053]    While laser line scanner  28 , in the preferred embodiment, creates vertically oriented line scans  36 , it is recognized and understood that other orientations of line scans  36  are possible depending upon the relative movement between laser line scanner  28 , food product  12  and line scan camera  32 .  
         [0054]    Various modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. It should be understood that this invention is not limited to the illustrative embodiments set forth above.