Abstract:
An expanding food storage container includes a base and a cover. The cover includes a support ring and a dome having a side wall closely received in the support ring. The support ring includes spaced tabs extending toward the side wall of the dome. The outer face of the dome sidewall includes a plurality of camming threads and support threads extending outward along helical paths. There is a pair of threads for each tab, with the threads spaced peripherally to closely receive the associated tab therebetween. Rotation of the dome with respect to the support ring causes the threads to ride up or down the tabs, raising or lowering the dome with respect to the support ring. The upper and lower ends of the threads include a horizontal slot which closely receives the associated tab. The tab includes a depression near its end which receives a lock button extending outward from the dome sidewall within the slot. The lock button may be selectively received within the depression to selectively secure the dome in the expanded or collapsed position.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is related to co-pending attorney reference number 131740-D200, which is incorporated by reference herein. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates in general to household food storage containers. In particular, the present invention relates to an improved food storage container which may expand or retract as needed for storage or use. 
         [0004]    It is well known to provide a base with cover to store or transport food. The cover may or course be removed for displaying or serving the food in the base. One common problem with this arrangement is the need to accommodate different amounts of food. For example, a base may have a cover which is slightly domed, defining together an enclosed space for storage. However, some larger food items, such as a roast or a tall cake, may not fit within this enclosed space. The usual solution to this problem is to provide a second cover having a larger dome which will accommodate the larger food item. This solution has drawbacks as it requires the purchase of a second cover, as well as increased storage space needed for the two covers. 
       SUMMARY OF THE INVENTION 
       [0005]    An object of the present invention is to provide an expanding food storage container with a base and a cover where the cover may selectively expand or collapse as needed. 
         [0006]    Another object of the present invention is to provide a cover for a food storage container which may expand or collapse as needed. 
         [0007]    A further object of the present invention is to provide such an expanding cover which may be locked in the expanded or collapsed positions. 
         [0008]    Yet another object of the present invention is to provide such an expanding cover which may suspend the entire container and food in either the expanded or collapsed positions. 
         [0009]    These and other objects are achieved by an expanding food storage container. The cover includes a support ring and a dome having a side wall closely received in the support ring. The support ring includes spaced tabs extending toward the side wall of the dome. The outer face of the dome sidewall includes a plurality of camming threads and support threads extending outward along helical paths. There is a pair of threads for each tab, with the threads spaced peripherally to closely receive the associated tab therebetween. Rotation of the dome with respect to the support ring causes the threads to ride up or down the tabs, raising or lowering the dome with respect to the support ring. The upper and lower ends of the threads include a horizontal slot which closely receives the associated tab. The tab includes a depression near its end which receives a lock button extending outward from the dome sidewall within the slot. The lock button may be selectively received within the depression to selectively secure the dome in the expanded or collapsed position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The objects and features of the invention noted above are explained in more detail with reference to the drawings, in which like reference numerals denote like elements, and in which: 
           [0011]      FIG. 1  is a top perspective view of the collapsible food storage container according to the present invention in the collapsed configuration; 
           [0012]      FIG. 2  is a top perspective view of the container cover in the expanded configuration; 
           [0013]      FIG. 3  is an exploded top perspective view thereof; 
           [0014]      FIG. 4  is a side view of the container cover the expanded configuration; 
           [0015]      FIG. 5  is a detailed cross-sectional view a long line  5 - 5 ; and 
           [0016]      FIG. 6  is a detailed cross-sectional view a long line  6 - 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    With reference to  FIG. 1 , a collapsible food storage container according to the present invention is generally designated by reference numeral  10 . The container  10  generally includes a base  12  and a cover  14 . The base  12  is shown as a generally flat disc in  FIG. 1 , but could alternatively be a shallow or deep bowl. The cover  14  may be secured to the base  12 , such as by a peripheral interlocking seal commonly known for food storage containers, a series of locking clamp tabs, etc. as are known in the art. In the preferred embodiment cover  14  is selectively secured to base  12  by a known arrangement of a locking tongue  16  received within a mating aperture in the base  12 , as shown in U.S. Pat. No. D389,018. As will be discussed more fully below, securing the cover  14  to the base  12  allows the user to lift the entire unit (with food inside) using a handle  18  on the top of cover  14 . 
         [0018]    As the base may be of a variety of forms, and the invention resides mainly in the cover  14 , the description below and the majority of the Figures will focus on cover  14 . The cover  14  includes a support ring  20  upon which is mounted a dome  22 , both of which are preferably formed of a suitable plastic. The support ring  20  generally takes the form of a section of a cylinder, with a cylindrical ring wall  24  having an upper end  26  and lower end  28 . As is best shown in  FIG. 3 , cover  14  includes at least two tabs  30  spaced about the periphery of the upper end  26  and extending radially inward. 
         [0019]    The dome  22  includes a generally cylindrical side wall  32  having an upper end  34  and lower end  36 . The ring wall  24  and the side wall  32  are sized such that one will closely fit within the other but still allow free relative rotation and longitudinal movement between the two. A series of camming threads  38  extend radially outward from side wall  32  and have a helical form as they extend from a position at or near the upper end  34  to the lower end  36  in a manner similar to screw threads. The tabs  30  on the support ring and the threads  38  extend toward one another and are sized so as to overlap. The threads  38  are also spaced about the periphery of the side wall  32  in a like manner corresponding to the spacing of the tabs  30 , and it is desired that there be at least one thread  38  associated with each tab  30 . Further, where there is one thread associated with each tab  30 , the threads  38  will all be spaced so as to contact a like edge of their associated tab  30 . For example, in the preferred embodiment shown, the threads are right-handed, and when viewed from above the threads  38  will all engage the tabs  30  at the right hand edge of the tabs  30  such that the camming thread  38  lies above (rather than below) the tab  30 . Stated another way, the camming threads  38  will each contact a leading edge  40  of the tabs  30 . 
         [0020]    Given the overlapping nature of the threads  38  to the tabs  30  it may be envisioned that the dome  22  is supported by the underside of threads  38  resting upon the associated tabs  30  at the leading edge  40 . It may also be envisioned that manual rotation of the dome  22  relative to the support ring will cause the dome  22  to move longitudinally upward or downward with respect to the support ring  20  in a manner similar to the screw moving inward or outward during placement or removal. In this way, it may be seen that the cover  14  may be moved from a collapsed configuration where the dome  22  is mainly received within the support ring  20  ( FIG. 1 ) to an expanded configuration where the dome  22  extends upward beyond the support ring  20  ( FIG. 2 ). With this expansion or collapse, it may be seen that the volume enclosed within the cover  14  will increase as the cover  14  expands and decrease as it collapses. 
         [0021]    The tabs  30  and the camming threads  38  will support the dome  22  and hold it against gravity relative to the support ring  20 . However, the camming threads  38  are inclined, and this support may not be as stable as desired. To help hold the dome  22  in the expanded position, one or more of the camming threads  38  may transition to a lower resting land  42 . Each of the lower resting lands  42  takes the form of a radially outward ledge extending horizontally about a portion of the periphery of the dome side wall  32  parallel to the lower end  36 . The depth of the lands  42  are preferably equal to that of the camming threads  38 . The length of the resting lands  42  is such to allow the tabs  30  to be received thereunder a sufficient amount so as to provide a stable resting position against gravity for the dome  22  when in the expanded position of  FIGS. 2 and 4 . 
         [0022]    While not required, it is preferred that the resting lands  42  be spaced from the lower end  36 , and that the lower end  36  include a peripheral flange  44  extending radially outward therefrom and having a depth similar to that of the lands  42 . The spacing between the lands  42  and the peripheral flange preferably forms a close sliding fit about the associated tabs  30 . This will provide a stable feel for the user when in the expanded position. 
         [0023]    It is also possible to form a lock button  46  protruding radially outward from the dome side wall  32  at a position between the resting lands  42  and the peripheral flange  44 . The tab  30  would then include a mating depression  47  extending radially inward. As may be envisioned, rotation of the dome  22  with respect to the ring  20  would cause the tabs  30  to move into the slots formed between the lands  42  and the flange  44 , with continued rotation causing the tab  30  to ride over the lock button  46  due to elastic deformation until that button  46  is received within the mating depression  47 . This would serve to selectively hold the dome  22  against unintended rotation. Further, the tabs  30  being closely received between the lands  42  and flange  44  would prevent upward or downward movement of the dome  22  relative to the ring  20 . In this manner, the cover  14  may be placed into a very secure expanded position. In fact, this can be so secure as to allow carrying of the fully loaded container  10  in this expanded position. Even so, the user may manually turn the dome  22  in the opposite direction to cause the tab  30  to again ride over the button  46  to release the dome and allow it to move to the collapsed position. 
         [0024]    While moving between the expanded and collapsed positions the camming threads  38  will support the dome  22  against gravity as described. However, there may be a tendency for the user to lift the dome  22  during rotation, causing the camming threads  38  to disengage from the tabs  30  and giving a loose feel to the container  10 . To avoid this, it is possible to space the camming threads a distance approximately equal to the length of the tabs  30  (not shown). In this manner the leading edge  40  of the tabs  30  would support the under side of a first camming thread  38 , while a trailing edge  48  of the same tab  30  would be closely adjacent to the upper side of the next adjacent camming thread  38 . This arrangement would be repeated about the cover  14 . As may be imagined, this would greatly reduce the amount of free vertical movement between the dome  22  and ring  20 , forcing a smooth rise and fall of the dome  22  with its rotation. 
         [0025]    While it is preferred to have this smooth rise and fall with rotation, for reasons made clear below it is not preferred to space the threads  38  equal to the tabs  30 . Instead, it is preferred that the camming threads  38  be spaced twice the length of the tabs  30 . To still have this smooth rise and fall, the dome side wall  32  further includes a plurality of support threads  50  extending radially therefrom. These support threads  50  are equal in number to the camming threads  38  and have a substantially identical depth and incline to threads  38 , but with each of the support threads  50  being spaced from its associated camming thread  38  by a distance just slightly greater than the length of the tab  30 . As such, there will be an alternating arrangement of camming thread  38 , support thread  50 , camming thread  38 , support thread  50 , etc. about the periphery of dome side wall  32 . In a manner similar to that described above, the leading edge  40  of a tab  30  will be in close proximity or contact with the under side of the associated camming thread  38 , while the trailing edge  48  of the tab  30  will be in close proximity or contact with the upper side of the associated support thread  50 . As with the first described arrangement, this would greatly reduce the amount of free vertical movement between the dome  22  and ring  20 , forcing a smooth rise and fall of the dome  22  with its rotation. 
         [0026]    In a manner similar to that described above for the camming thread  38 , it is preferred that one or more of the support threads have an upper resting land  52  transitioning therefrom, and extending in the opposite radial direction to that of the lower resting lands  42 . The upper lands  52  would preferably have a similar length to that of the lower lands  42 . As may be envisioned, these upper lands  52  would prevent continued upward movement of the dome  22  with respect to the ring  20 . Also similarly to the previous arrangement, an upper peripheral flange  54  extends radially outward from the upper end  34  of the dome side wall  32 , thus combining with the upper resting lands  52  creating one or more slots to receive the tab  30  when in the collapsed position. Also as before, a lock button  46  may protrude from the dome side wall  32  within this slot so as to selectively mate with a depression  56  in the outer face of the tab  30 . 
         [0027]    The tab  30  may include one centrally located mating depression, such that the depression  47  and the depression  56  are one and the same and would mate with either the upper or the lower lock button  46 . In practice, however, this is not preferred, and the tab  30  would include separate depressions  47  and  56  each located near a respective end of the tab  30 . This is because the tab  30  must ride over the button  46  via elastic deformation of the tab  30  (or more likely the entire ring wall  24 ). To provide the desired strength, however, it is desired that the tabs  30  be relatively long. As such, it is preferred that the two depressions be used at positions relatively close to the ends of the tab  30  to make this locking function easier to perform for the user. 
         [0028]    Yet another variation is preferred for the container  10 , this one allowing improved assembly. As may be envisioned, to initially assemble the dome  22  with the ring  20  the tabs  30  must elastically deform to ride over either the peripheral flange  44  or the upper peripheral flange  54 . To avoid this, it is preferred that the upper peripheral flange be discontinuous, as shown. In particular, the upper peripheral flange would be present only in those areas immediately over the upper resting lands  52 . This will form gaps or openings in the upper flange  54  corresponding to the pairs of threads  38  and  50  which contain the tabs  30 . As such, the dome  22  could freely fall downward relative to the ring  20  when so aligned. When the ring  20  is mounted to the base  12  this is prevented by the base blocking this motion. However, when the cover  14  is removed from the base  12 , this assembly or disassembly of the dome  22  from the ring  20  becomes quite simple. 
         [0029]    As may be seen, with this arrangement the dome  22  may be locked in either the expanded or the collapsed positions due to engagement of the buttons  46  with the appropriate depressions  47  or  56 , and with the resting lands and peripheral flanges fully supporting the tabs  30 . In this manner, the user may lift, carry and transport the container  10  using handle  18  in both the collapsed and the expanded condition. Further, even during the rotating transition between expanded and collapsed positions the container will feel stable due to the use of the camming threads  38  and support threads  50  each closely receiving the tabs  30 . 
         [0030]    From the foregoing it will be seen that this invention is one well adapted to attain all ends and objects set forth above together with the other advantages which are inherent within its structure. 
         [0031]    It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
         [0032]    Since many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth of shown in the accompanying drawings is to be interpreted as illustrative, and not in a limiting sense.