Abstract:
A method of manufacturing an artificial seed blank ( 20 ) is provided. The method includes placing a seed shell ( 22 ) on one of a plurality of receptacles ( 72 ) at the first assembly station. The method also includes depositing media ( 26 ) into the seed shell and positioning the seed shell at a second assembly station. The method also includes removing the seed blank from the receptacle at the second assembly station.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     The present application claims the benefit of U.S. Provisional Application No. 60/525,434, filed Nov. 25, 2003. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention relates generally to artificial seeds and, more particularly, to a method and system of manufacturing seed blanks for manufactured seeds.  
       BACKGROUND OF THE INVENTION  
       [0003]     Asexual propagation for plants has been shown for some species to yield large numbers of genetically identical embryos, each having the capacity to develop into a normal plant. Such embryos must usually be further cultured under laboratory conditions until they reach an autotrophic “seedling” state characterized by an ability to produce their own food via photosynthesis, resist desiccation, produce roots able to penetrate soil, and fend off soil microorganisms. Some researchers have experimented with the production of artificial seeds, known as manufactured seeds, in which individual plant somatic or zygotic embryos are encapsulated in a seed coat. Examples of such manufactured seeds are disclosed in U.S. Pat. No. 5,701,699, issued to Carlson et al., the disclosure of which is hereby expressly incorporated by reference.  
         [0004]     Typical manufactured seeds include a seed shell, synthetic gametophyte and a plant embryo. A manufactured seed that does not include the plant embryo is known in the art as a “seed blank.” The seed blank typically is a cylindrical capsule having a closed end and an open end. The synthetic gametophyte is placed within the seed shell to substantially fill the interior of the seed shell. A longitudinally extending hard porous insert, commonly known as a cotyledon restraint, may be centrally located within the synthetic gametophyte and includes a centrally located cavity extending partially through the length of the cotyledon restraint. The cavity is sized to receive the plant embryo therein. The well-known plant embryo includes a radicle end and a cotyledon end. The plant embryo is deposited within the cavity of the cotyledon restraint cotyledon end first and is sealed within the seed blank by at least one end seal. There is a weakened spot in the end seal to allow the radicle end of the embryo to penetrate the end seal.  
         [0005]     Currently, the seed shell is manufactured by hand and is formed from sectioning a tube, such as a straw, and processing the sections of the tube to enhance its abilities to withstand exposure to the environment. One such seed shell is manufactured by sectioning a straw of fibrous material, and then coating the resulting straw section with a wax. One suitable method for applying the wax coating is to dip the straw sections into a bath of wax. The straw sections are then withdrawn from the wax bath and then the wax is permitted to harden to seal the straw sections.  
         [0006]     Although such seed blanks are effective, they are not without their problems. As a non-limiting example, because the current process of manufacturing seed blanks is manual, it is labor-intensive and, therefore, expensive. Additionally, because such existing processes are manual, manipulation and manufacture of a large number of seed blanks in accordance with existing practice can be time-intensive. As a result, mass production of manufactured seeds is not only time-consuming, but also expensive.  
         [0007]     Thus, there exists a need for a method and system of manufacturing artificial seed blanks that can manipulate and assemble a large number of seed blanks at a relatively low cost, with a high degree of reliability, and without adversely affecting the quality of resulting seed blanks.  
       SUMMARY OF THE INVENTION  
       [0008]     In a material handling system having means for automatically assembling and transporting an artificial seed blank between a plurality of assembly stations arranged in a sequential configuration, a method of manufacturing an artificial seed blank is provided. The method includes placing a seed shell on one of a plurality of receptacles at a first assembly station, and depositing media into the seed shell. The method also includes positioning the seed shell at a second assembly station, and removing the seed shell from the receptacle at the second assembly station.  
         [0009]     In accordance with another embodiment of the present invention, the method further includes heating at least one of the plurality of receptacles before placing a seed shell on one of the plurality of receptacles. Another embodiment also includes depositing a restraint on one of the plurality of receptacles before placing a seed shell on one of the plurality of receptacles. In still yet another embodiment, the method includes positioning the seed shell at a cooling station after depositing media into the seed shell to accelerate a state change of the media.  
         [0010]     A material handling system for automatically assembling and transporting an artificial seed blank between a plurality of assembly stations arranged in a sequential configuration is also provided. The material handling system includes a transport assembly having a plurality of receptacles, each one of the plurality of receptacles is adapted to receive an artificial seed shell. A drive assembly is coupled to the transport assembly to selectively transport at least one of the plurality of receptacles between the plurality of assembly stations. The material handling system also includes a cooling assembly in communication with a portion of the transport assembly to accelerate a change in state of media disposed within the seed shell.  
         [0011]     In yet another embodiment of the present invention, the material handling system includes a heater in communication with at least one of the plurality of receptacles, wherein the heater is adapted to preheat the receptacle. Further, a seed shell handling system is also suitably part of another embodiment of the present invention. The seed shell handling assembly is adapted to place a seed shell on one of the plurality of receptacles.  
         [0012]     The method and system of manufacturing artificial seed blanks, as well as the resulting manufactured seed blank, formed in accordance with the various embodiments of the present invention, have several advantages over currently available methods. The method and system of the present disclosure is simpler to operate as it consolidates various parts of the assembly procedure at substantially one location. Also, because such a method and system is automated, it reduces manual labor required to manipulate and assemble seed blanks and, therefore, is cheaper than existing systems.  
         [0013]     Thus, a method and system of manufacturing artificial seed blanks in accordance with the various embodiments of the present invention has a high degree of reliability, and is capable of mass producing artificial seed blanks at a relatively low cost. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The foregoing aspects and many of the attendant advantages of this invention will become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0015]      FIG. 1  is a cross-sectional side view of a manufactured seed blank formed in accordance with various embodiments of the present invention;  
         [0016]      FIG. 2  is an isometric view of one embodiment of a material handling system for automatically assembling and transporting an artificial seed blanks between a plurality of assembly stations; and  
         [0017]      FIG. 3  is a partial isometric view of a portion of the material handling system of  FIG. 2 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]      FIG. 1  illustrates a seed blank  20  constructed in accordance with certain embodiments of the present invention. Such a seed blank  20  is suitably used for a manufactured seed, such as is disclosed in U.S. Pat. No. 5,701,699, issued to Carlson et al., the disclosure of which is hereby expressly incorporated by reference.  
         [0019]     The seed blank  20  includes a seed shell  22 , a cotyledon restraint  24  and an end seal  28 . The end seal  28  is shown for illustrative purposes only and is not a necessary element of the present invention.  
         [0020]     The seed shell  22  is suitably formed from a tube. In one embodiment, the tube is a straw of fibrous material, such as paper, and is sectioned in appropriate lengths. The sections of straw are pretreated in a suitable coating material, such as wax. As another non-limiting example, the tubes are formed from a biodegradable plastic material. One such tube is sold by Biocorp North America of Los Angeles, Calif. Such biodegradable plastic tubes are similarly sectioned into appropriate lengths for use as a manufactured seed. Further, such biodegradable plastic tubes do not require a wax coating as such tubes are already resistive to environmental elements. It should be apparent that although sectioning tube is preferred, other embodiments, such as obtaining tubes of appropriate size for use as manufactured seeds, are also within the scope of the present invention.  
         [0021]     The cotyledon restraint  24  is suitably manufactured from a hard, porous material and includes a stem  96  and longitudinally extending cavity  30 . The open end of the cavity  30  is known as a cotyledon restraint opening  32 . The cavity  30  is sized to receive a plant embryo (not shown) therein. The seed blank  20  also includes synthetic gametophyte  26  disposed within the seed shell  22 , as is described in greater detail below.  
         [0022]     A material handling system  40  for automatically assembling and transporting seed blanks  20  between a plurality of assembly stations is best seen by referring to  FIGS. 2 and 3 . The material handling system  40  includes a transport assembly  42 , a heater  44 , a cooling assembly  46 , a media filler assembly  48 , and a restraint handling assembly  50 .  
         [0023]     The transport assembly  42  includes a carousel  60  operatively connected to a drive assembly  62  by a spindle shaft  64  extending through a platform  66 . The drive assembly  62  is suitably a well-known motor, such as a stepper motor or a well known AC or DC motor. The spindle shaft  64  is suitably a rod extending between the drive assembly  62  and a disc-shaped holder plate  68 . The spindle shaft  64  is coupled to the holder plate  68  by a well known bearing  70 .  
         [0024]     Disposed around the perimeter of the holder plate  68  is a plurality of receptacles  72 , commonly referred to as “pucks.” The receptacles  72  suitably hang from the holder plate  68  by a pin  74 . Each receptacle  72  also includes a seat  76  sized to receive a cotyledon restraint  24 . As coupled to the holding plate  68 , the receptacles  72  are disposed in a substantially circular configuration. Although a substantially circular configuration of receptacles is preferred, other sequential configurations, such as an oval or substantially linear configuration, are also within the scope of the present invention.  
         [0025]     As may be best seen by referring to  FIG. 3 , the restraint handling assembly  50  will now be described in greater detail. The restraint handling system  50  includes a feeder arm  90 , a guide arm  92 , and a pusher assembly  94 . The feeder arm  90  is suitably coupled to a reservoir (not shown) containing a plurality of cotyledon restraints  24 . The cotyledon restraints  24  are stored within the reservoir and are fed onto the feeder arm  90 , such that the stem  96  of the cotyledon restraint  24  is positioned upwards. The cotyledon restraint  24  slides down the feeder arm  90  where it intersects and slides onto the guide arm  92 .  
         [0026]     The guide arm  92  includes a bridge  98  extending from one end of the guide arm  92 . During operation of the material handling system  40 , receptacles  72  are selectively displaced into a position adjacent the free end of the bridge  98 , as is described in greater detail below.  
         [0027]     The pusher assembly  94  is suitably a hydraulically operated mechanism that includes a push rod  100  positioned to selectively slide the cotyledon restraint  24  along a track  102  of the guide arm  92  and onto the bridge  98  when a receptacle  72  is located adjacent the free end of the bridge  98 . The pusher assembly  94  slides the cotyledon restraint  24  off of the bridge  98  and into the seat  76  of the receptacle  72 . After the cotyledon restraint  24  is disposed on the receptacle  72 , the drive assembly  62  conditionally actuates the transport assembly  42  to a second assembly station, where a seed shell  22  is coupled to the cotyledon restraint  24  by the seed shell handling assembly  43 .  
         [0028]     The seed shell handling assembly  43  includes an arm  110  having a tweezer assembly  112  operatively connected to one end of the arm  110 . The tweezer assembly  112  is suitably a controllable pickup device adapted to selectively retrieve seed shells  22  from a reservoir (not shown). The seed shell handling assembly  43  positions a seed shell  22  above the stem  96  of the cotyledon restraint  24 . As positioned, the arm  110  selectively displaces the seed shell  22  downwardly, such that the cotyledon restraint  24  is received within the seed shell  22 . The tweezer assembly  112  then releases the seed shell  22 , and the arm  110  raises upwardly and away from the now-joined cotyledon restraint  24  and seed shell  22 .  
         [0029]     Although it is preferred that the arm  110  actuates downwardly to place the seed shell  22  into contact with a cotyledon restraint  24 , it should be apparent that other methods, such as displacing the transport assembly  42  upwardly to place the cotyledon restraint  24  into contact with the seed shell  22 , are also within the scope of the present invention. It should also be apparent that although a material handling system  40  having both a restraint handling assembly  50  and a seed shell handling assembly  43  is preferred, they are optional to the operation of such a system. As a nonlimiting example, a seed shell and cotyledon restraint may be preassembled at a location separate from the material handling system  40 , such that a seed shell already including a cotyledon restraint disposed therein may be placed onto the receptacle either by hand, the seed shell handling assembly  43 , or an equivalent apparatus. Accordingly, such embodiments are also within the scope of the present invention.  
         [0030]     Referring back to  FIG. 2 , the media filler assembly  48  will now be described in greater detail. The media filler assembly  48  includes a filler arm  120  and a dispensing nozzle  122  in fluid communication with the filler arm  120 . The filler arm  120  is operatively connected to a reservoir (not shown) containing liquid gametophyte. The dispensing nozzle  122  is suitably located above a bore  170  extending through a portion of the cooling assembly  46 . Although the present embodiment describes the dispensing nozzle  122  as located proximate to a bore extending through the cooling assembly, other embodiments, such as locating the dispensing nozzle before the cooling assembly, are also within the scope of the present invention.  
         [0031]     When a seed shell  22  is located beneath the dispensing nozzle  122 , the media filler assembly  48  selectively dispenses a predetermined amount of gametophyte  26  into the open end of the seed shell  22 . The exact amount of gametophyte dispensed into the seed shell  22  varies according to the volume of the seed shell  22 . In one preferred embodiment, the seed shell  22 , including the cotyledon restraint  24 , is filled with gametophyte  26  to a predetermined volume that is less than the total available volume after the cotyledon restraint  24  is disposed within the seed shell  22 . As a non-limiting example, the predetermined volume of gametophyte  26  disposed within the seed shell  22  is about 10 to 50 mm 3  less than the total available volume of the seed shell  22  containing the cotyledon restraint  24 . The exact volume is determined to permit attachment of the dead end seal (not shown) to the resulting seed blank  20 . Accordingly, the predetermined amount of gametophyte is a direct function of the size and shape of a seed shell  22  and, in certain embodiments, is less than the total volume available. After the predetermined amount of gametophyte is dispensed into the seed shell  22  at this assembly station, the material handling system  40  selectively transports the seed shell  22  to the cooling assembly  46 .  
         [0032]     The cooling assembly  46  is a well known chiller and only portions are shown for ease of description. The cooling assembly  46  includes a chiller box  130  substantially encasing a plurality of receptacles  72  to accelerate a state change of gametophyte  26  within the seed shells  22 . Specifically, the cooling assembly  46  accelerates the rate by which the gametophyte  26  changes state from a substantially liquid state to a gelatin-like state. Also, the cooling assembly  46  may assist in bonding the cotyledon restraint  24  within the seed shell  22  for those embodiments where the cotyledon restraint  24  and seed shell  22  are coupled together as part of the seed blank  20  manufacturing process. Specifically, before the gametophyte  26  is deposited within the seed shell  22 , the seed shell  22  is passed through a portion of the cooling assembly  46 , thereby accelerating the rate at which the seed shell  22  and cotyledon restraint  24  are bonded. Although it is preferred that the cooling assembly  46  pre-cool the combination seed shell and cotyledon restraint, other embodiments, such as permitting the seed shell and cotyledon restraint bond under ambient conditions, are also within the scope of the present invention. After completion of the cooling stage, the combination of the seed shell  22 , cotyledon restraint  24 , and gametophyte  26  is commonly referred to as a “seed blank.” 
         [0033]     Although a plurality of receptacles  72  are illustrated as being disposed within the cooling assembly  46 , other embodiments, such as only one receptacle  72  within the chiller box  130 , are also within the scope of the present invention. Also, the cooling assembly  46  is an optional component of the material handling system  40  and, therefore, other embodiments, such as material handling systems that do not include a cooling assembly, are also within the scope of the present invention.  
         [0034]     After the cooling cycle has been completed, the drive assembly  62  selectively actuates the transport assembly  42  to a discharge station  140 . At the discharge station  140 , the seed blank  20  is removed from the receptacle  72  and into a holding bin  142  by a pneumatically or hydraulically actuated arm  144 . Specifically, the arm  144  moves in a direction indicated by the arrow  146 , thereby knocking the seed blank  20  off of the receptacle  72  and into the holding bin  142 . Thereafter, the seed blanks are transported to another location where an embryo is inserted within the cotyledon restraint  24  and an end seal (not shown) is applied to the open end of the seed blanks  20  to seal the embryo within the seed blank  20 .  
         [0035]     Still referring to  FIG. 2 , the heater  44  will now be described in greater detail. In that regard, a collar  150  housing heating coil or a warm air blower assembly (not shown) substantially encases a plurality of receptacles  72 . As housed within the collar  150 , heat is either radiated or blown onto the receptacles  72  to raise the temperature of each receptacle  72 , such that when the seed shell  22  is placed onto a cotyledon restraint  24  by the seed shell handling assembly  43 , heat from the receptacle  72  melts and bonds the cotyledon restraint  24  within the seed shell  22 . Although a plurality of receptacles  72  are illustrated as being disposed within the collar  150 , it should be apparent that other embodiments, such as a collar housing only a single receptacle, are also within the scope of the present invention. Also, it should be apparent that a heater is an option to the material handling system  40  of the present invention and, therefore, other embodiments, such as a material handling system without a heater, are also within the scope of the present invention.  
         [0036]     A summary of the method of the present embodiment is best understood by referring to  FIG. 2 . In that regard, at least one receptacle  72  is preheated by the heater  44  to a desired temperature. After the desired temperature is achieved, the drive assembly  62  selectively rotates the transport assembly  42  in a direction indicated by the arrow  152 , into another assembly station to receive a cotyledon restraint  24  from the restraint handling assembly  50 .  
         [0037]     At this assembly station, the cotyledon restraint  24  is selectively displaced onto the seat  76  by the push rod  100 . Thereafter, the receptacle  72  containing the cotyledon restraint  24  is transported to another assembly station where the seed shell  22  is placed onto the cotyledon restraint  24  by the seed shell handling assembly  43 , as described above.  
         [0038]     After the seed shell  22  is placed onto the cotyledon restraint  24 , the transport assembly  42  is again actuated to yet another assembly station, where gametophyte  26  is displaced into the open end of the seed shell  22  by the media filler assembly  48 . Once again, the drive assembly  62  actuates the transport assembly  42  to move the receptacle  72  into the cooling assembly  46 , where the state change of the gametophyte  26  disposed within the seed shell  22  is accelerated by the reduced temperature within the chiller box  130 .  
         [0039]     The transport assembly  42  continues to rotate about the spindle shaft  64 , thereby rotating the receptacle  72  into the discharge station  140 , where the seed blank  20  is deposited into the holding bin  142  by the arm  144 . Although the method and system of the present invention has only been described with respect to a single seed shell  22  being disposed on a single receptacle  72 , it should be apparent that other embodiments are also within the scope of the present invention. As a nonlimiting example, as the receptacle  72  is transported being various assembly stations, multiple seed blanks may be in various stages of assembly. Thus, multiple seed shells may be simultaneously assembled utilizing the material handling system and method of the present invention.  
         [0040]     From the foregoing description, it can be seen that the method and system of manufacturing artificial seed coats formed in accordance with the embodiments of the present invention incorporate many novel features and offers significant advantages over currently available systems. While the presently preferred embodiments of the invention have been illustrated and described, it is to be understood that, within the scope of the appended claims, various changes can be made therein without departing from the spirit of the invention.  
         [0041]     As a nonlimiting example, various assembly stations may be combined at a single location. Specifically, the seed shell handling assembly and media filler assembly may be accomplished at a single location. In that regard, after the seed shell handling assembly  43  displaces a seed shell  22  onto a cotyledon restraint  24 , the media filler assembly  48  may be displaced into proximity to the open end of the seed shell  22  to dispense media into the seed shell  22  at the same location where the seed shell handling assembly  43  placed the seed shell  22  onto the cotyledon restraint  24 . Accordingly, such embodiments are also within the scope of the present invention.