Abstract:
A battery tray for storing a battery comprises: a battery storage unit comprising: a first side and a second side facing each other, and a third side and a fourth side facing each other, wherein the third and fourth sides have planar portions for accommodating a prismatic battery cell and round portions for accommodating a cylindrical battery cell; a first guiding unit extending from a lower portion of the third side to secure a first end of a prismatic battery cell; and a second guiding unit extending from a lower portion of the fourth side to secure a second end of a prismatic battery cell.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional Application No. 61/352,287, filed on Jun. 7, 2010, the entire content of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     Aspects of the present invention relate to a battery storage tray. 
     2. Description of the Related Technology 
     Rechargeable batteries, which can be repeatedly charged and are small-sized, large-capacity batteries, are typically used as power sources for various portable electronic devices, such as notebook computers, camcorders, cellular phones, etc. 
     In the manufacture of a rechargeable battery, the battery typically subjected to an aging process to effectuate its capability as a proper battery. The aging process is typically a process for charging a rechargeable battery immediately after the rechargeable battery is formed. At this stage, the rechargeable battery typically generates an electrochemical energy by electrical energy supplied thereto. 
     The aging process is typically performed on a plurality of rechargeable batteries. To this end, a tray for storing the plurality of rechargeable batteries is required. 
     SUMMARY 
     According to one aspect of the present invention, a battery tray for storing a battery comprises: a battery storage unit comprising: a first side and a second side facing each other, and a third side and a fourth side facing each other, wherein the third and fourth sides have planar portions for accommodating a prismatic battery cell and round portions for accommodating a cylindrical battery cell; a first guiding unit extending from a lower portion of the third side to secure a first end of a prismatic battery cell; and a second guiding unit extending from a lower portion of the fourth side to secure a second end of a prismatic battery cell. 
     According to an embodiment, the battery storage tray includes a plurality of battery storage units. 
     According to an embodiment, the battery storage unit further comprises a through-hole at a lower surface of the battery tray to expose a terminal of a battery cell accommodated therein. 
     Since multiple types of batteries can be stored in a single battery storage unit, the manufacturing cost of battery storage trays according to embodiments can be reduced. Further, the storage space required for storing multiple types of battery storage trays can also be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a battery storage tray according to an embodiment of the present invention; 
         FIG. 2  is a plan view of the battery storage tray shown in  FIG. 1 ; 
         FIG. 3  is an enlarged plan view illustrating a state in which a first prismatic battery is stored in a single battery storage unit shown in  FIG. 2 ; 
         FIG. 4  is a cross-sectional view of the battery storage unit taken along the line A-A′ of  FIG. 3 ; 
         FIG. 5  is a cross-sectional view of the battery storage unit taken along the line B-B′ of  FIG. 3 ; 
         FIG. 6  is a cross-sectional view of the battery storage unit taken along the line C-C′ of  FIG. 3 ; 
         FIG. 7  is a perspective view of a first guide unit of the battery storage unit shown in  FIG. 3 ; 
         FIG. 8  is an enlarged plan view illustrating a state in which a second prismatic battery is stored in a single battery storage unit shown in  FIG. 2 ; 
         FIG. 9  is a cross-sectional view illustrating a positional relationship between each of the first and second prismatic batteries and the first guide unit shown in  FIG. 3 ; 
         FIG. 10  is a cross-sectional view of the battery storage unit taken along the line D-D′ of  FIG. 3  in a state in which a cylindrical battery is stored in the single battery storage unit shown in  FIG. 2 ; 
         FIG. 11  is a cross-sectional view illustrating a portion of a battery storage tray according to another embodiment of the present invention, the portion corresponding to the battery storage tray portion shown in  FIG. 6 ; 
         FIG. 12  is a perspective view of a first guide unit of the battery storage unit shown in  FIG. 11 ; and 
         FIG. 13  is a plan view illustrating a portion of a battery storage tray according to still another embodiment of the present invention, the portion corresponding to the battery storage tray portion shown in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION 
     Certain embodiments will now be described more fully hereinafter with reference to the accompanying drawings. 
       FIG. 1  is a perspective view of a battery storage tray according to an embodiment of the present invention, and  FIG. 2  is a plan view of the battery storage tray shown in  FIG. 1 . 
     Referring to  FIG. 1 , the battery storage tray  10  may be formed of an injection mold having a substantially hexagonal shape, and may include a first surface  10   a , a second surface  10   b  opposite to the first surface  10   a , and a third surface  10   c  connecting the first surface  10   a  and the second surface  10   b.    
     Referring to  FIG. 2 , the battery storage tray according to an embodiment  10  includes a battery storage unit  100  in which a battery is received through the first surface  10   a , and a through-hole  200  is formed at a predetermined area of the second surface  10   b , the predetermined area corresponding to the battery storage unit  100 . The battery storage tray  10  can store a plurality of batteries to be used for an aging process. Accordingly, a plurality of battery storage units  100  may be provided in the battery storage tray  10 . The aging process may be a process for charging batteries before shipment, and may be performed by making probe pins contact an electrode terminal of a battery exposed through an upper part of the battery storage unit  100  and another electrode terminal of the battery exposed through the through-hole  200 , and by applying a charging current to the respective electrode terminals. Embodiments of the invention will next be described with regard to one battery storage unit among the plurality of battery storage units  100  constituting the battery storage tray  10 . 
       FIG. 3  is an enlarged plan view illustrating a state in which a first prismatic battery is stored in a single battery storage unit shown in  FIG. 2 ,  FIG. 4  is a cross-sectional view of the battery storage unit taken along the line A-A′ of  FIG. 3 ,  FIG. 5  is a cross-sectional view of the battery storage unit taken along the line B-B′ of  FIG. 3 ,  FIG. 6  is a cross-sectional view of the battery storage unit taken along the line C-C′ of  FIG. 3 , and  FIG. 7  is a perspective view of a first guide unit of the battery storage unit shown in  FIG. 3 . 
     Referring to  FIG. 3 , the battery storage unit  100  may provide a space S 10  in which a battery is stored. In detail, the battery storage unit  100  may include a first space S 1  having a substantially rectangular shape, in which a prismatic battery is stored, a second space S 2  having a substantially cylindrical shape, in which a cylindrical battery is stored, and a third space S 3  in which a holding device for holding the prismatic battery or the cylindrical battery is entered. Herein, the prismatic battery is defined as a battery having a plane shape such as square, rectangular, oval and so on. In order to facilitate storage of the prismatic battery or the cylindrical battery, the battery storage unit  100  may include a taper surface  100   a  formed on the upper portion of the space S 10 . To form the space S 10 , the battery storage unit  100  may include a first side surface  110 , a second side surface  120 , a third side surface  130 , a fourth side surface  140 , and a bottom surface  150 . In addition, the battery storage unit  100  may include a first guide unit  160  and a second guide unit  170  to guide and arrange multiple types of prismatic batteries (for example, prismatic batteries having different thicknesses) stored in the space S 10 . 
     The first side surface  110  and the second side surface  120  may face each other with a prismatic battery, for example, a first prismatic battery  1  having a first thickness T 1  stored in the first space S 1 , interposed therebetween, and may be formed to be planar. The first side surface  110  and the second side surface  120  can restrict the first prismatic battery  1  from moving in a width direction WD. Here, the first thickness T 1  may be, for example, 4 mm. Meanwhile, the first prismatic battery  1  may include a top surface from which the electrode terminal  2  protrudes, a side surface having a round portion  1   a  and a planar portion  1   b , and a bottom surface opposite the top surface. The first side surface  110  and the second side surface  120  may face approximately the round portion  1   a  of the side surface of the first prismatic battery  1 . 
     The third side surface  130  and the fourth side surface  140  may connect the first side surface  110  and the second side surface  120 , and face each other with the first prismatic battery  1  interposed therebetween. In detail, the third side surface  130  and the fourth side surface  140  face approximately the planar portion  1   b  of the side surface of the first prismatic battery  1 . The third side surface  130  and the fourth side surface  140  can restrict the first prismatic battery  1  from moving in rotation directions RD 1  and RD 2 . 
     In detail, the third side surface  130  may include first planar portions  130   a  and  130   b , first round portions  130   c  and  130   d , a first protruding portion  130   e , and a first holding portion  130   f . The first planar portions  130   a  and  130   b  may be connected to a first end of the first side surface  130  and a first end of the second side surface  140 , respectively, and may be formed approximately at right angles with respect to the first side surface  130  and the second side surface  140 . In addition, the first planar portions  130   a  and  130   b  may be formed to be planar. The first round portions  130   c  and  130   d  may extend from the first planar portions  130   a  and  130   b  and extend outwardly from the central axis CA to have round shapes. The first protruding portion  130   e  may be formed in such a manner that a portion of the first planar portion  130   b  protrudes toward the first prismatic battery  1 . The first holding portion  130   f  may be connected between the first round portion  130   c  and the first round portion  130   d , and have a round shape protruding outwardly from the central axis CA further than the first round portions  130   c  and  130   d . The taper surface  100   a  may not be formed at a portion of the upper portion of the battery storage unit  100  corresponding to the first holding portion  130   f.    
     In detail, the fourth side surface  140  may include second planar portions  140   a  and  140   b , second round portions  140   c  and  140   d , a second protruding portion  140   e , and a second holding portion  140   f . The second planar portions  140   a  and  140   b  may be connected to a second end of the first side surface  110  and a second end of the second side surface  120 , respectively, and may be formed approximately at right angles with respect to the first side surface  110  and the second side surface  120 . In addition, the second planar portions  140   a  and  140   b  may be formed to be planar. The second round portions  140   c  and  140   d  may extend from the second planar portions  140   a  and  140   b  and may be symmetrical with the first round portions  130   c  and  130   d  about the central axis CA. The second protruding portion  140   e  may be formed in such a manner that a portion of the second planar portion  140   b  may protrude toward the first prismatic battery  1 , and face the first protruding portion  130   e  in a diagonal direction. The second holding portion  140   f  may be connected between the second round portion  140   c  and the second round portion  140   d , and may be symmetrical to the first holding portion  130   f  about the central axis CA. The taper surface  100   a  may not be formed at a portion of the upper portion of the battery storage unit  100  corresponding to the second holding portion  140   f.    
     The bottom surface  150  may connect the first side surface  110 , the second side surface  120 , the third side surface  130  and the fourth side surface  140  to one another. In detail, the bottom surface  150  may include a first bottom surface  150   a  and a second bottom surface  150   b . The first bottom surface  150   a  can face the bottom surface of the first prismatic battery  1  stored in the first space S 1 . The second bottom surface  150   b  may contact the bottom surface of a cylindrical battery ( 5  of  FIG. 10 ) stored in the second space S 2  and may extend to an area corresponding to the third space S 3 . The second bottom surface  150   b  may be positioned higher than the first bottom surface  150   a.    
     As described above, the first side surface  110 , the second side surface  120 , the first planar portions  130   a  and  130   b , the second planar portions  140   a  and  140   b , and the first bottom surface  150   a  can form the first space S 1  in which the first prismatic battery  1  is stored. Here, the first prismatic battery  1  having the first thickness T 1  may be stored in the first space S 1  while rotating in the rotation direction RD 2 . As shown in  FIGS. 5 and 6 , the first protruding portion  130   e  and the second protruding portion  140   e  may come into contact with the side surface of the first prismatic battery  1 . In detail, the first protruding portion  130   e  and the second protruding portion  140   e  may come into line contact or point contact with an area right before the round portion  1   a  of the planar portion  1   b  that is a partial portion of the side surface of the first prismatic battery  1 . The first protruding portion  130   e  and the second protruding portion  140   e  can support and fix the first prismatic battery  1 . 
     As shown in  FIG. 7 , the first guide unit  160  may be formed to protrude on the first bottom surface  150   a  so as to come into contact with lower parts of the first planar portion  130   a  and the first side surface  110 . In detail, the first guide unit  160  may include a first guide inclined surface  160   a  and a first guide side surface  160   b.    
     The first guide inclined surface  160   a  may be a surface inclined in directions of the central axis CA and the first bottom surface  150   a  at the lower part of the first planar portion  130   a  spaced apart from the first bottom surface  150   a . The first guide inclined surface  160   a  may be in contact with the first planar portion  130   a  and the first bottom surface  150   a . In addition, the farther from the first prismatic battery  1  in the width direction WD of the first prismatic battery  1 , the wider the first guide inclined surface  160   a  can become. 
     The first guide side surface  160   b  may be connected to the first guide inclined surface  160   a , the first planar portion  130   a , and to the first bottom surface  150   a.    
     When the first prismatic battery  1  is rotationally inserted into the first space S 1 , the first guide unit  160  can guide the first prismatic battery  1  to rotate in the rotation direction RD 2  by the first guide inclined surface  160   a . In addition, the first guide unit  160  can fix the first prismatic battery  1  by the first guide inclined surface  160   a  so as to prevent the rotated first prismatic battery  1  from moving. 
     The second guide unit  170  may be formed to protrude on the first bottom surface  150   a  so as to come into contact with lower parts of the second planar portion  140   b  of the fourth side surface  140  and the second side surface  120 . Since the second guide unit  170  can be shaped to be symmetrical with the first guide unit  160  about the central axis CA in a diagonal direction, detailed description thereof will not be given. The second guide unit  170  can guide rotation of the first prismatic battery  1  in the rotation direction RD 2  in cooperation with the first guide unit  160  when the first prismatic battery  1  is rotationally inserted into the first space S 1 . In addition, the second guide unit  170  can fix the first prismatic battery  1  in cooperation with the first guide unit  160  so as to prevent the rotated first prismatic battery  1  from moving. 
     Next, an embodiment in which a second prismatic battery  3  having a second thickness T 2  is stored in the aforementioned battery storage unit  100  will be described. 
       FIG. 8  is an enlarged plan view illustrating a state in which a second prismatic battery is stored in a single battery storage unit shown in  FIG. 2 . 
     Referring to  FIG. 8 , the second prismatic battery  3  having a second thickness T 2  can include a top surface from which the electrode terminal  4  protrudes, a side surface having a round portion  3   a  and a planar portion  3   b , and a bottom surface opposite to the top surface. Here, the second thickness T 2  of the second prismatic battery  3  may be greater than the first thickness T 1  of the first prismatic battery  1 . The second thickness T 2  of the second prismatic battery  3  may be, for example, 7 mm. The second prismatic battery  3  may be stored in the first space S 1  without being rotated. Thus, it is understood that prismatic batteries having different thicknesses can be stored in the first space S 1  with different rotation rates. Meanwhile, since a connection relationship between each of the first protruding portion  130   e  and the second protruding portion  140   e  and the second prismatic battery  3  is the same as that between each of the first protruding portion  130   e  and the second protruding portion  140   e  and the first prismatic battery  1 , detailed description thereof will not be given. 
     The positional relationship between each of the first prismatic battery  1  and the second prismatic battery  3  and the first guide unit  160  will now be described. 
       FIG. 9  is a cross-sectional view illustrating the positional relationship between each of the first and second prismatic batteries and the first guide unit shown in  FIG. 3 . 
     Referring to  FIG. 9 , the first prismatic battery  1  having the first thickness T 1  can rotationally move to the lower part of the first guide inclined surface  160   a  by the first guide inclined surface  160   a  of the first guide unit  160  to then be positioned at a first height H 1  from the first bottom surface  150   a . By contrast, the second prismatic battery  3  having the second thickness T 2  does not rotationally move along the inclined surface  160   a  of the first guide unit  160 , so that it is positioned at a second height H 2  from the first bottom surface  150   a . From this perspective, it can be easily appreciated that the smaller the thickness of a prismatic battery, the more the prismatic battery can rotationally rotate along the inclined surface  160   a  of the first guide unit  160 . 
     Although not shown in the drawing, the positional relationship between each of the first prismatic battery  1  and the second prismatic battery  3  and the second guide unit  170  may be the same as that between each of the first prismatic battery  1  and the second prismatic battery  3  and the first guide unit  160 . 
     Next, an embodiment in which a cylindrical battery  5  is stored in the single battery storage unit  100  shown in  FIG. 2  will be described. 
       FIG. 10  is a cross-sectional view of the battery storage unit taken along the line D-D′ of  FIG. 3  in a state in which a cylindrical battery is stored in a single battery storage unit shown in  FIG. 2 . 
     Referring to  FIG. 10 , the cylindrical battery  5  having a top surface from which an electrode terminal  6  protrudes may be stored in the second space S 2 . The second space S 2  may be formed by the first round portions  130   c  and  130   d , the second round portions  140   c  and  140   d  and the second bottom surface  150   b , which are shown in  FIG. 3 . 
     As described above, the battery storage tray  10  according to an embodiment of the present invention includes the battery storage unit  100  providing the first space S 1  in which the first guide unit  160  and the second guide unit  170  are formed, and the second space S 2 , thereby storing multiple types of batteries, that is, prismatic batteries having different thicknesses as well as a cylindrical battery, in a single battery storage unit  100 . 
     Therefore, the battery storage tray  10  according to an embodiment of the present invention can reduce the manufacturing cost of the battery storage tray required by battery type and reduce the storage space required for storing multiple types of battery storage trays. 
     Next, a battery storage tray according to another embodiment of the present invention will be described. 
       FIG. 11  is a cross-sectional view illustrating a portion of a battery storage tray according to another embodiment of the present invention, the portion corresponding to the battery storage tray portion shown in  FIG. 6 .  FIG. 12  is a perspective view of a first guide unit of the battery storage unit shown in  FIG. 11 . 
     The battery storage tray according to another embodiment of the present invention has substantially the same configuration and functions as those of the battery storage tray  10  according to an embodiment, except for the configuration of a first guide unit  360  of a battery storage unit  300 . Thus, the battery storage tray according to the present embodiment will be described with emphasis on the first guide unit  360  of the battery storage unit  300 . 
     Referring to  FIGS. 11 and 12 , the first guide unit  360  of the battery storage unit  300  may be formed to protrude on a first bottom surface  150   a  so as to come into contact with lower parts of a first planar portion  130   a  and a first side surface  110 . The first guide unit  360  of the battery storage unit  300  may be similar to the first guide unit  160  of the battery storage unit  100 , except that it has two inclined surfaces. In detail, the first guide unit  360  may include a first guide inclined surface  360   a , a second inclined surface  360   b , and a first guide side surface  360   c.    
     The first inclined surface  360   a  may be a surface inclined in directions of the central axis CA and the first bottom surface  150   a  at the lower part of the first planar portion  130   a  spaced apart from the first bottom surface  150   a . The first guide inclined surface  360   a  may be in contact with the first planar portion  130   a  but may not be in contact with the first bottom surface  150   a . In addition, the farther from the first prismatic battery  1  in the width direction WD of the first prismatic battery  1 , the wider the first guide inclined surface  160   a  becomes. 
     The second inclined surface  360   b  may be an inclined surface connecting the first inclined surface  360   a  and the first bottom surface  150   a . The farther from the first prismatic battery  1  in the width direction WD of the first prismatic battery  1 , the wider the second inclined surface  360   b  can become. According to embodiments, the second inclined surface  360   b  has a slope that is steeper than that of the first inclined surface  360   a.    
     The first guide side surface  360   c  may be connected to the first inclined surface  360   a , the second inclined surface  360   b , the first planar portion  130   a , and the first bottom surface  150   a.    
     When the first prismatic battery  1  is rotationally inserted into the first space S 1 , the first guide unit  360  can guide the first prismatic battery  1  to rotate in a more secured, flexible manner by the first guide inclined surface  360   a  and the second inclined surface  360   b . In addition, the first guide unit  360  can more securely fix the first prismatic battery  1  by the first guide inclined surface  360   a  or the second inclined surface  360   b  so as to prevent the rotated first prismatic battery  1  from moving. Here, the second inclined surface  360   b  can be advantageous for fixing a prismatic battery having a relatively small thickness. 
     Since a second guide unit (not shown) may be shaped to be symmetrical with the first guide unit  360  about the central axis CA in a diagonal direction, it is not illustrated in the drawing and a detailed description thereof will not be given. The second guide unit may function to guide rotation of the first prismatic battery  1  in a more secured, flexible manner in cooperation with the first guide unit  360  when the first prismatic battery  1  is rotationally inserted into the first space S 1 , and can more securely fix the rotated first prismatic battery  1  so as to prevent the first prismatic battery  1  from moving. 
     As described above, the battery storage tray according to another embodiment of the present invention may include the battery storage unit  300  providing the first space S 1  in which the first guide unit  360  having two inclined surfaces and the second guide unit are formed, thereby storing prismatic batteries having different thicknesses in a single battery storage unit  300  in a more secured, flexible manner. 
     Next, a battery storage tray according to another embodiment of the present invention will be described. 
       FIG. 13  is a plan view illustrating a portion of a battery storage tray according to another embodiment of the present invention, the portion corresponding to the battery storage tray portion shown in  FIG. 3 . 
     The battery storage tray according to another embodiment of the present invention has substantially the same configuration and functions as those of the battery storage tray  10 , except that a battery storage unit  400  further includes a fourth space S 14 . Thus, the battery storage tray according to the present embodiment will be described with emphasis on the fourth space S 14  of the battery storage unit  400 . 
     Referring to  FIG. 13 , the battery storage unit  400  can provide a space S 20  in which a battery is stored. In detail, the battery storage unit  400  may include a first space S 1  having a substantially rectangular shape, in which a prismatic battery is stored, a second space S 2  having a substantially cylindrical shape, in which a cylindrical battery is stored, a third space S 3  in which a holding device for holding the prismatic battery or the cylindrical battery is entered, and a fourth space S 14  having a substantially rectangular shape, in which another prismatic battery is stored. In order to facilitate storage of the prismatic battery or the cylindrical battery, the battery storage unit  100  may include a taper surface  100   a  formed on the upper portion of the space S 20 . 
     To form the space S 20 , the battery storage unit  400  may include a first side surface  110 , a second side surface  120 , a third side surface  130 , a fourth side surface  140 , a fifth side surface  410 , a sixth side surface  420 , a seventh side surface  430 , an eighth side surface  440 , and a bottom surface  450 . The seventh side surface  430  may include a third protruding portion  430   e , the eighth side surface  440  may include a fourth protruding portion  440   e , and the bottom surface  450  may include a first bottom surface  150   a , a second bottom surface  150   b  and a third bottom surface  450   c . The fourth space S 14  of the battery storage unit  400  and the first space S 1  may intersect with each other and form substantially an ‘X’ shape. The fourth space S 14  may be formed by the fifth side surface  410 , the sixth side surface  420 , the seventh side surface  430 , the eighth side surface  440 , and the third bottom surface  450   c . The fifth side surface  410 , the sixth side surface  420 , the seventh side surface  430 , the eighth side surface  440 , and the third bottom surface  450   c  may have substantially the same configurations and functions as those of the first side surface  110 , the second side surface  120 , the third side surface  410 , the fourth side surface  140 , and the first bottom surface  150   a  forming the first space S 1 , except for their formed positions, and thus detailed descriptions thereof will not be given. 
     In addition, the battery storage unit  400  may include a first guide unit  160 , a second guide unit  170 , a third guide unit  460  and a fourth guide unit  470  to guide and arrange multiple types of prismatic batteries (for example, prismatic batteries having different thicknesses) stored in the space S 20 . 
     The third guide unit  460  and the fourth guide unit  470  may be formed on the third bottom surface  450   c . The third guide unit  460  and the fourth guide unit  470  may have substantially the same configurations and functions as those of the first guide unit  160  and the second guide unit  170  formed on the first bottom surface  150   a , except for their formed positions, and thus detailed descriptions thereof will not be given. 
     The third side surface  130  and the eighth side surface  440  may be connected by first round portions  480   a  and  480   b . In addition, the fourth side surface  140  and the seventh side surface  430  may be connected by second round portions  490   a  and  490   b . A taper surface  100   a  may not be formed at areas of an upper part of the battery storage unit  400  corresponding to the first round portion  480   b  and the second round portion  490   b.    
     According to embodiments, the first side surface  110 , the second side surface  120 , the third side surface  130 , and the fourth side surface  140  are sized to accommodate a prismatic battery cell having a first length, while the fifth side surface  410 , the sixth side surface  420 , the seventh side surface  430  and the eighth side surface  440  are sized to accommodate a prismatic battery cell having a second length. 
     As described above, the battery storage tray according to still another embodiment of the present invention includes the battery storage unit  400  providing the first space S 1  and the fourth space S 14  for storing prismatic batteries, thereby storing multiple types of batteries in a single battery storage unit  400  in more various manners. 
     Although the present invention has been described with reference to certain embodiments thereof, it will be understood by those skilled in the art that a variety of modifications and variations may be made to the present invention without departing from the spirit or scope of the present invention defined in the appended claims, and their equivalents.