Abstract:
A leaf removal apparatus for removing one or more wrapper leaves of a harvested produce and its method of use is provided. The apparatus includes a framework, a conveyor comprising a set of parallel rods having a space therebetween, a stripping roller, and a plurality of flexible members. The methods of using the apparatus include feeding a harvested produce onto a conveyor comprising a set of parallel rods having a space therebetween; transporting the harvested produce on the conveyor towards a stripping roller connected to a framework of the leaf removal apparatus; contacting the harvested produce with a plurality of flexible members connected to the framework, and the stripping roller, and loosening or removing one or more wrapper leaves of the harvested produce, wherein one or more of the removed wrapper leaves fall through the space between the rods of the conveyor.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation of U.S. patent application Ser. No. 14/742,429, filed Jun. 17, 2015, which is a Divisional of U.S. patent application Ser. No. 13/742,319, filed Jan. 15, 2013, now U.S. Pat. No. 9,078,468, which are hereby incorporated by reference in their entirety. 
    
    
     BACKGROUND 
     1. Field 
     The present disclosure relates generally to commercial produce processing, and more specifically to mechanically removing wrapper leaves from a harvested produce. 
     2. Related Art 
     The commercial produce industry is a multi-billion dollar industry. For example, lettuce is produced and shipped year round in the U.S. with the source of supplies changing with the seasons, with California and Arizona dominating U.S. production. Three types of lettuce dominate commercial production: iceberg, leaf lettuce, and romaine lettuce. Of these three types, iceberg lettuce makes up the majority of the commercial lettuce production in the U.S. 
     Conventionally, the harvesting of lettuce is predominately performed by hand. Field workers will typically hand cut the lettuce from its roots, and place the cut lettuce on a moving platform for subsequent processing and packaging. As part of the subsequent processing steps, outer leaves of the cut lettuce is typically removed for various reasons, such as unpalatable texture. These outer leaves that loosely wrap around a lettuce head are also referred to as “wrapper leaves”. The removal of wrapper leaves is conventionally a labor-intensive process performed by field workers, which requires workers to manually remove the wrapper leaves without damaging the delicate lettuce head. 
     Thus, what is needed in the art is a way to efficiently remove wrapper leaves from a harvested produce head without damaging the produce head before sending the produce head for further processing and packaging. 
     BRIEF SUMMARY 
     In one exemplary embodiment, an apparatus for removing one or more wrapper leaves of a harvested produce is provided. The apparatus includes a framework, a stripping roller, a conveyor, and a plurality of flexible members. The conveyor is configured to transport the harvested produce towards the stripping roller. The stripping roller is connected to the framework, and is configured to rotate and exert a frictional force on the harvested produce to remove one or more wrapper leaves of the harvested produce. A gap exists between the stripping roller and the output end of the conveyor, and one or more of the removed wrapper leaves may fall through the gap. The plurality of flexible members is also connected to the framework, and hangs vertically over the output end of the conveyor or over the gap. These flexible members are configured to loosen or remove one or more wrapper leaves of the harvested produce as the harvested produce moves across the gap, and may also help to rotate the harvested produce as it is moving down the conveyor causing one or more wrapper leaves to peel off. 
     Also provided is a mechanical method of removing one or more wrapper leaves of a harvested produce using a leaf removal apparatus. The method includes feeding a harvested produce onto a conveyor; transporting the harvested produce on the conveyor towards a stripping roller connected to a framework of the leaf removal apparatus; and contacting the harvested produce with the stripping roller to remove one or more wrapper leaves. The stripping roller is configured to rotate and exert a frictional force on the harvested produce to remove one or more wrapper leaves of the harvested produce. A gap exists between the stripping roller and the output end of the conveyor, and one or more of the removed wrapper leaves may fall through the gap. The method may also further include contacting the harvested produce with a plurality of flexible members connected to the framework. The flexible members hang vertically over the output end of the conveyor or over the gap, and are configured to loosen or remove one or more wrapper leaves of the harvested produce. The flexible members may also help to rotate the harvested produce as it is moving down the conveyor causing one or more wrapper leaves to peel off. 
    
    
     
       DESCRIPTION OF THE FIGURES 
       The present application can be best understood by references to the following description taken in conjunction with the accompanying figures, in which like parts may be referred to by like numerals: 
         FIGS. 1A, 1B, 1C, and 1D  depict an exemplary embodiment of a leaf removal apparatus and the removal of wrapper leaves from a harvested produce; 
         FIG. 2  depicts a free-body diagram of a harvested produce in the leaf stripping area of the leaf removal apparatus, illustrating the forces exerted on the harvested produce by the conveyor, a flexible member, and the stripping roller; 
         FIGS. 3A  (top view) and  3 B (front view) depict different view of the leaf-stripping area in the exemplary embodiment of  FIG. 1 . 
         FIG. 4  depicts another exemplary embodiment of a leaf removal apparatus with two sets of flexible members, where one set hangs over the conveyor before reaching the leaf stripping area, and the other set hangs over the gap between the stripping roller and the output end of the conveyor in the leaf stripping area; 
         FIG. 5  depicts yet another exemplary embodiment of a leaf removal apparatus with two leaf stripping areas; and 
         FIG. 6  is a flow chart depicting an exemplary method of removing one or more wrapper leaves of a harvested produce using a leaf removal apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     To provide a more thorough understanding of the present invention, the following description sets forth numerous specific details, such as specific configurations, parameters, examples, and the like. It should be recognized, however, that such description is not intended as a limitation on the scope of the present invention but is intended to provide a better description of exemplary embodiments. 
     With reference to  FIGS. 1A-D , an exemplary leaf removal apparatus  100  is depicted. As described below, apparatus  100  is configured to remove one or more wrapper leaves  132  from harvested produce  130 . As depicted in  FIGS. 1A-D , in the present embodiment, harvested produce  130  is iceberg lettuce, which is also commonly referred to as crisphead or head lettuce. It should be understood, however, that apparatus  100  may be used for other types of harvested produce. For example, apparatus  100  may be used to remove wrapper leaves of harvested leaf lettuce, romaine lettuce or cabbage. 
     With reference to  FIG. 1A , apparatus  100  includes framework  104 , flexible members  106 , stripping roller  108 , and conveyor  102 . In this exemplary embodiment, flexible members  106  and stripping roller  108  are connected to framework  104 . Both are positioned and configured to work together to remove one or more wrapper leaves  132  from harvested produce  130  in leaf stripping area  110 . Apparatus  100  also includes conveyor  102 , which is configured to receive and transport harvested produce  130  towards leaf stripping area  110 . While in some embodiments, conveyor  102  may be connected to framework  104 , conveyor  102  may have its own independent framework. 
     With reference again to  FIG. 1A , conveyor  102  is configured to receive harvested produce  130  at input end  101 , and transport harvested produce  130  towards leaf-stripping area  110 . As depicted in  FIG. 1A , in this exemplary embodiment, conveyor  102  is made up of a set of parallel rods  140 . It should be understood, however, that in other embodiments, conveyor  102  may be a belt. Moreover, as depicted in  FIG. 1A , in this exemplary embodiment, conveyor  102  wraps around sprockets  150  and  152 . Once rods moving away from input end  101  reach leaf stripping area  110 , the rods wrap around sprocket  152  and move back towards input end  101 . It should be understood, however, that in other embodiments, conveyor  102  may be configured differently. For example, conveyor  102  may be configured such that rollers may be used in lieu of sprockets. 
     With reference to  FIG. 1B , in this exemplary embodiment where the conveyor is made up of a set of parallel rods, conveyor  102  is configured to have space  142  between two rods. Space  142  is narrow enough to avoid harvested produce  130  from falling through, but wide enough to allow detached wrapper leaf  131  to fall through space  142  onto the ground. It should be understood that if conveyor  102  is a belt, as discussed above, space  142  may not exist in such a configuration of the leaf removal apparatus, since the belt would be a continuous piece of material. 
     With reference to  FIG. 1C , in this exemplary embodiment, output end  103  of conveyor  102 , flexible members  106 , and stripping roller  108  work together in leaf stripping area  110  to loosen and remove one or more wrapper leaves  132 . Flexible members  106  may facilitate the removal of one or more wrapper leaves from harvested produce  130  in a number of ways. For example, as depicted in  FIG. 1C , flexible members  106  brush over the surface of harvested produce  130  and may loosen one or more wrapper leaves  132  from harvested produce  130 . In other instances (not depicted in  FIG. 1C ), one or more wrapper leaves may completely detach from the harvested product as a result of the contact with the flexible members. Further, flexible members  106  may slow down the forward movement of harvested produce  130  or even hold the produce over the gap (element  112 ) between the output end of the conveyor and the stripping roller. As such, flexible members  106  may help to prolong the duration of contact between harvested produce  130  and stripping roller  108 . Flexible members  106  may also help to rotate harvested produce  130  as it is moving down conveyor  102  causing one or more wrapper leaves to peel off. 
     While flexible members  106  are depicted in  FIGS. 1A-D  as hanging vertically over gap  112 , it should be recognized that in other embodiments, flexible members  106  may hang vertically over output end  103  of conveyor  102 . 
     Flexible members  106  may be made of any flexible material that would not damage harvested produce  130  upon contact. For example, flexible members  106  can be formed from urethane. Flexible members  106  may also take different forms. For example, flexible members  106  may be in form of ropes. 
     With reference to  FIG. 1D , stripping roller  108  (as depicted) rotates counterclockwise. When harvested produce  130  comes in contact with stripping roller  108 , stripping roller  108  may loosen wrapper leaf  132  from harvested produce  130 , or remove wrapper leaf  132 . Flexible members  106  can help to push any loosen wrapper leaves into gap  112 , causing the stripped wrapper leaf to fall to the ground. 
     Stripping roller  108  can be made of any material, such as rubber, metal, or plastic. In some embodiments, the surface of stripping roller  108  is textured. The texture can help to create a frictional force useful for loosening and removing one or more of the wrapper leaves. Any texture on stripping roller  108 , however, is selected to minimize damage to the inner leaves of the harvested produce. It should be understood that the texture of the surface of stripping roller  108  may vary depending on the type, size, and maturity of the harvested produce processed. For example, when the produce is harvested at a less mature stage, the wrapper leaves are typically more tightly attached to the harvested produce. As such, the stripping roller may be textured to generate enough of frictional force to loosen and remove wrapper leaves. It should also be understood that, in certain embodiments, the surface of the stripping roller can be smooth if the material of the stripping roller can create a frictional force to help remove the wrapper leaves. 
       FIG. 2  is a free-body-diagram depicting some of the forces that can be exerted on harvested produce  130  while in contact with the conveyor, flexible members, and stripping roller. The conveyor imparts force  202  on harvested produce  130 . The flexible members, which provide some resistance against harvested produce  130 , impart force  204  on the harvested produce  130 . One of skill in the art would recognize that force  204  is the sum of forces  204 A and  204 B. The stripping roller, which rotates in a counterclockwise direction, imparts force  206  on harvested produce  130 . One of skill in the art would recognize that force  206  is the sum of forces  206 A and  206 B. 
     The sum of forces  202 ,  204 A and  206 A (as depicted in  FIG. 2 ) determines whether harvested produce remains in the gap between the stripping roller and the output end of the conveyor or moves forward beyond the gap, for example, to a second conveyor, a container, or another processing station. For example, if force  202  exceeds the sum of force  204 A and  206 A, then harvested produce  130  would tumble forward past the gap. If force  202  equals the sum of force  204 A and  206 A, then harvested produce  130  would sit in the gap until another harvested produce from behind pushes harvested produce  130  forward. 
     Forces  204 B and  206 B are depicted in  FIG. 2  as downward forces that can contribute to the removal of wrapper leaves on harvested produce  130 . For example, if the flexible member comes in contact with one or more wrapper leaves where force  204  is exerted, the downward component of force  204  (i.e., force  204 B) can help to loosen and remove one or more wrapper leaves from harvested produce  130 . Similarly, if the stripping roller comes in contact with one or more wrapper leaves where force  206  is exerted, the downward component of force  206  (i.e., force  206 B) can help to loosen and remove one or more wrapper leaves from harvested produce  130 . 
     The amount of force exerted on harvested produce  130  by the conveyor, flexible members, and stripping roller may vary based on numerous factors including the type of produce processed, the maturity of the harvested produce, and the pace at which harvested produce are fed onto the conveyor. The amount of force  202  exerted by the conveyor may be varied by controlling the speed of the conveyor. The amount of force  204  exerted by the flexible members may be varied by the type of material used. The amount of force  206  exerted by the stripping roller may be varied by controlling the rotational speed of the stripping roller. The speed of the conveyor and the rotational speed of the stripping roller may be coordinated to optimize the overall forces exerted on the harvested produce. For example, in one embodiment, the ratio between the rotational speed of the stripping roller to the speed of the conveyor is between 1 to 4 (e.g., 1, 2, 3 or 4). 
     With reference to  FIGS. 3A and 3B , several other factors may be optimized to control effectiveness of leaf removal of apparatus  100  including, for example, the diameter of the stripping roller, the width of the gap between the stripping roller and the output end of the conveyor, the length of the flexible members, and the width between each flexible member. 
     With reference to  FIG. 3A , the diameter (element  122 ) of stripping roller  108  may be varied depending on the type, size and maturity of the produce used on apparatus  100 . Diameter  122  is typically between 0.5 inch and 5 inches. In an exemplary embodiment where harvested produce is iceberg lettuce, diameter  122  of stripping roller  108  may be about 1.5 inches. 
     With reference again to  FIG. 3A , gap  112  exists between the longitudinal axis of stripping roller  108  and the horizontal edge of output end  103  of conveyor  102 . The width (element  120 ) of gap  112  may be varied depending on the type, size and maturity of the produce used on apparatus  100 . Width  120  is typically between 0.5 to 3 inches. In one embodiment where harvested produce is iceberg lettuce, width  120  is about 1 inch. It should be understood that width  120  may be wider if harvested produce  130  is larger in size, and narrower if harvested produce  130  is smaller in size. 
     With reference to  FIG. 3B , length  124  of the flexible members may be varied depending on the type, size and maturity of the produce used on apparatus  100 . Length  124  is typically between 6 to 24 inches. In one embodiment where harvested produce is iceberg lettuce, length  124  is about 12 inches. It should be understood that length  124  may be longer if harvested produce  130  is larger in size, and shorter if harvested produce  130  is smaller in size. It should be understood that while flexible members  106  may all be the same length, the lengths may also be unequal and differ slightly from one flexible member to another. 
     With reference again to  FIG. 3B , width  126  between two flexible members may be varied depending on the type, size and maturity of the produce used on apparatus  100 . Width  126  is typically between 1 to 10 inches. In one embodiment where harvested produce is iceberg lettuce, width  126  is about 4 inches. It should be understood that width  126  may be wider if harvested produce  130  is larger in size, and narrower if harvested produce  130  is smaller in size. It should be understood that while the space between two flexible members  106  may all be the same width, the widths may also be unequal and differ slightly between one set of adjacent flexible members to another set of adjacent flexible members. 
     Additionally, while  FIG. 3B  depicts two flexible members in contact with harvested produce  130 , it should be understood that harvested produce  130  may not always be in contact with two flexible members. For example, in some instances, harvested produce  130  may be in contact with only one flexible member, and wrapper leaves  132  may still be loosened and removed as described above. 
     While apparatus  100  depicted in  FIGS. 1-3  has one set of flexible members, in other exemplary embodiments, a leaf removal apparatus may have one of more additional sets of flexible members. For example, the additional sets of flexible members may be positioned outside of the leaf-stripping area.  FIG. 4  depicts an exemplary leaf removal apparatus  400  that has a second set of flexible members  407 . In other embodiments, leaf removal apparatus may not have any flexible members. In such an embodiment, the conveyor and stripping roller are positioned and configured to work together to loosen and remove one or more wrapper leaves from a harvested produce. 
     With reference to  FIG. 4 , apparatus  400  includes framework  404 , a first set of flexible members  406 , a second set of flexible members  407 , stripping roller  408 , and conveyor  402 . In this exemplary embodiment, flexible members  406  and stripping roller  408  are connected to framework  404 , and are positioned and configured to work together to remove one or more wrapper leaves  432  from a harvested produce  430  in leaf stripping area  410 . A second set of flexible members  407  is connected to framework  404 , and hangs vertically over conveyor  402 . In this exemplary embodiment, flexible members  407  comes in contact with harvested produce  430  before the harvested produce reaches leaf stripping area  410 . Flexible members  407  can help to loosen and even remove loose wrapper leaves  432  of harvested produce  430 , before the harvested product reaches leaf stripping area  410 . 
     While apparatus  100  depicted in  FIGS. 1-3  has one leaf stripping area, in other exemplary embodiments, a leaf removal apparatus may have more two or more leaf-stripping areas.  FIG. 5  depicts an exemplary leaf removal apparatus  500  that has two leaf stripping areas,  510  and  520 . Apparatus  500  includes conveyors  502  and  512 , flexible members  506  and  516 , and stripping rollers  508  and  518 . The first conveyor, i.e., conveyor  502 , is configured to move a plurality of harvested produce towards leaf stripping area  510 , where the harvested produce comes into contact with flexible members  506  and stripping roller  508 . In some instances, apparatus  500  may have removed all the wrapper leaves of a given harvested produce; but in other instances, apparatus may have only loosed the wrapper leaves of the harvested produce, or removed some of the wrapper leaves. Apparatus  500  also includes a second conveyor, i.e., conveyor  512 , configured to receive harvested produce from leaf stripping area  510  and to move the harvested produce towards leaf stripping area  520 , where the harvested produce comes into contact with flexible members  516  and stripping roller  518  to remove one or more of any remaining wrapper leaves on the harvested produce. Additionally, apparatus  500  includes conveyor  522  configured to receive harvested produce from leaf stripping area  520 , and to move the harvested produce to a container or bin, or another processing station, such as a washing, inspection or packaging station. 
     While  FIGS. 1-5  depict exemplary leaf removal apparatuses as a standalone apparatus, the leaf removal apparatus may be part of a larger mechanical harvester. For example, the leaf removal apparatus may be connected to a cutting and transporting apparatus of a mechanical harvester. The cutting and transporting apparatus can sever produce in the field, transport the harvested produce to the back of the mechanical harvester, and deliver the harvested produce to the input end of a conveyor of the leaf removal apparatus. The leaf removal apparatus may also be connected to one or more processing stations, including for example stations for inspecting, sorting, washing, and packaging the harvested produce. 
     Provided herein is also a method for removing wrapper leaves of produce. With reference to  FIG. 6 , process  600  depicts an exemplary process for removing one or more wrapper leaves of a harvested produce using any of the leaf removal apparatuses described herein. In step  602 , a harvested produce is fed onto a conveyor of a leaf removal apparatus. The conveyor may be connected to a framework of the leaf removal apparatus, or the conveyor may have its own independent framework. In step  604 , the harvested produce is transported on the conveyor towards the leaf stripping area of the leaf removal apparatus. The leaf area includes the output end of the conveyor, as well as the stripping roller and a plurality of flexible members both of which are connected to the framework of the leaf removal apparatus. As discussed above, however, flexible members may not be present in certain embodiments of the leaf removal apparatus. 
     In this exemplary method, the leaf removal apparatus used has a set of flexible members that hang vertically over the leaf stripping area. With reference again to  FIG. 6 , in step  606 , the harvested produce comes into contact with the flexible members, which are configured to loosen or remove one or more wrapper leaves. In step  608 , the harvested produce comes into contact with the stripping roller, which is configured to rotate and exert a force to remove one or more wrapper leaves. It should be understood that steps  606  and  608  may occur at about the same time in the leaf stripping area (depicted by box  620 ). 
     As described above with respect to the exemplary leaf removal apparatuses, a gap exists between the longitudinal axis of stripping roller and the horizontal edge of the output end of the conveyor. One or more of the removed wrapper leaves may fall through this gap, to prevent these wrapper leaves from moving on in the harvesting process. 
     In step  610 , the stripped harvested produce moves across the gap of the leaf stripping area and falls onto a second conveyor, a container, or another processing platform or station. The stripped harvested produce may move across the gap, away from the leaf stripping area, by momentum of the harvested produce as it was transported by the conveyor. Additionally, the stripped harvested produce may move across the gap by a push from a second harvested produce from behind. It should be understood that a plurality of harvested produce may be processed using the leaf removal apparatus described above. 
     The foregoing descriptions of specific embodiments have been presented for purposes of illustration and description. They are not intended to be exhaustive, and it should be understood that many modifications and variations are possible in light of the above teaching.