Abstract:
A two-piece, lockable, wedge-shaped container is disclosed which includes a tray portion having upstanding peripheral walls, the front wall of which is higher than the other side walls, and a sleeve portion having a top wall for covering the tray, a smaller bottom wall and a front opening. When fully inserted into the sleeve, the tall front wall of the tray deforms the sleeve top wall and front opening as it passes therethrough, and prevents the tray from being removed from the sleeve thereby locking the tray and sleeve together.

Description:
FIELD OF THE INVENTION 
     The present invention is directed toward a lockable two-piece container, and more specifically, toward a container comprising a sleeve and a tray slidably receivable and selectively lockable within the sleeve. 
     BACKGROUND OF THE INVENTION 
     The fast-food industry uses a wide variety of containers and packaging for serving various food products. One common type of container comprising a base portion and an integral lid connected by a living hinge is often referred to as a “clamshell” container. Such containers are in widespread use, especially for relatively small products such as sandwiches and chicken nugget products. While such containers are versatile and relatively inexpensive, they are not well adapted for use with larger food products. 
     Pizza, for example, is generally sold in square boxes formed from a relatively heavy grade of corrugated cardboard. Such containers are suitable for holding entire pizza pies, which may be 16 inches in diameter or larger. However, restaurants often sell pizza by the individual slice, or are called upon to wrap one or several slices in a “doggie bag” for patrons who have eaten at the restaurant. To make the slices easy to carry, customers may be given a pizza box large enough for an entire pizza to hold the one or several slices, or the slices may be wrapped in foil. The former method is wasteful, as a large amount of heavy cardboard is used to hold as little as one slice of pizza. This method can also be messy—a single slice of pizza is apt to slide from side to side in a large pizza box, and may be damaged when carried by a patron. The latter method provides no support for the pizza and the wrapping often sticks to the melted pizza cheese. Furthermore, a foil-wrapped slice of pizza generally requires two hands to carry, and when the pizza is wrapped and given to the customer hot, the foil provides very little thermal insulation. 
     Clamshell containers have also been used for individual pizza slices. U.S. Pat. No. 5,788,145, for example, shows a one-piece, triangular clamshell container useful for holding a single slice of pizza. A single pizza slice, however, is often 8 to 10 inches long. A hinged clamshell container for this slice would therefore be at least 16 to 20 inches long when open. While such containers can be nested when stored, their length makes them awkward to use and may present storage difficulties—they may be too long to fit on a shelf having a normal width, for example. Such containers can be stored in a closed configuration to reduce their length, but in this configuration they cannot be nested and they take up a large volume of space, again leading to storage inefficiencies. 
     It would therefore be desirable to provide a storage container for a single slice of pizza or similar food product that is easy to use and that can be stored in a space-efficient manner while still providing the benefits of an inexpensive, lockable clamshell-type container. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes these and other problems by providing a two piece, lockable container shaped to accommodate a slice of pizza. While the preferred embodiment will be described herein in terms of a container for a single slice of pizza, it will be appreciated that the container could also be used to hold multiple slices of pizza or to hold other wedge shaped items such as slices of pie or cheese, or even various non-food items. 
     The preferred embodiment of the invention comprises a wedge-shaped tray with upstanding peripheral walls and a blunt front end which walls and front end define a top opening for receiving a slice of pizza. The tray is preferably about one inch deep, but can be sized appropriately for different types of product—thin pizzas versus deep-dish pizzas, for example. The top opening is larger than the tray bottom wall so that multiple trays can be nested. The invention further comprises a separate wedge-shaped sleeve having a narrow front end and wide back end for receiving the tray and holding the tray in place after insertion in the sleeve. The sleeve includes a top wall slightly larger than the top opening of the tray and depending side walls defining a front opening about the same size as the tray front wall end. The side walls are located only near the front opening to reduce the amount of paperboard needed for the sleeve. The sleeve side walls include fold lines running parallel to the top wall which allow the side walls, and hence the sleeve, to collapse and be stored in a flat configuration. 
     The front end of the tray comprises a wall somewhat taller than the rest of the tray peripheral walls and also somewhat taller than the height of the sleeve front opening when the sleeve is in an open configuration with its top wall parallel to its bottom wall. However, the sleeve is flexible enough to permit the passage of this oversized wall portion. In use, therefore, a slice of pizza is place into the tray and the blunt front end of the tray is passed under the rear end of the sleeve and toward the front sleeve opening. As the bottom side of the tray bottom wall engages the top side of the sleeve bottom wall, the top edge of the tray front wall is pushed up against the underside of the tray top wall. The flexible top wall bows outwardly to allow the tray to pass. The tray and sleeve are sized so that the tray front wall can pass just beyond the sleeve front opening before the tray side walls engage the sleeve side walls to stop further movement. As the tray front end exits the sleeve, the sleeve top wall returns to a generally flat configuration. Because the tray front end is taller than the sleeve front opening in its relaxed state, the tray is effectively locked in place and will not slide out of the sleeve. To remove the tray, the sleeve or tray or both must be deformed to allow the tray to pass back through the sleeve front opening. 
     It is therefore a principal object of the present invention to provide a lockable two-piece container. 
     It is another object of the invention to provide an improved two-piece wedge-shaped container. 
     It is a further object of the present invention to provide a sleeve cover for a tray which sleeve covers less than the entire bottom wall of the tray. 
     It is still another object of the present invention to provide a passive locking mechanism for a paperboard container comprising a tray and a sleeve. 
     It is still a further object of present invention to provide a two piece tray and sleeve container wherein the tray portion is stackable and the sleeve portion is collapsible for space efficient storage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects of the invention will be better understood after reading the following detailed description of the preferred embodiment of the invention in connection with the following drawings, wherein: 
     FIG. 1 is a top plan view of the tray portion of the container of the subject invention; 
     FIG. 2 is a bottom plan view of the tray of FIG. 1; 
     FIG. 3 is a front elevation view of the tray of FIG. 1; 
     FIG. 4 is a top plan view of the sleeve portion of the container of the subject invention; 
     FIG. 5 is a bottom plan view of the sleeve shown in FIG. 4; 
     FIG. 6 is a front elevation view of the sleeve of FIG. 4; 
     FIGS. 7-9 are side elevation views of the tray of FIG. 1 being inserted into the sleeve of FIG. 4; 
     FIG. 10 is a bottom plan view of the subject tray locked in the subject sleeve; 
     FIG. 11 is a top plan view of a blank used to form the tray of FIG. 1; and, 
     FIG. 12 is a top plan view of the blank used to form the sleeve of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting same, FIGS. 1 and 2 show a tray  10  comprising a generally triangular tray bottom  12  having a top face  14  and a bottom face  16 . Tray  12  includes four peripheral walls extending upwardly and outwardly from the periphery of the bottom wall including a back wall  18  having a top edge  19 , a front wall  20  having a top edge  21 , and a first side wall  22  having a top edge  23  and a second side wall  24  with a top edge  25 , which side walls extend between the front and back walls. Front wall  20  is narrower than back wall  18 , and therefore the side walls converge toward the front wall in the direction from the rear wall. 
     In this preferred embodiment, the front wall has a small width; however the width of the front wall could be increased or even decreased until the tray bottom was essentially triangular. In such case the front wall would comprise the thickness of the end portions of the converging side walls, and would function in a similar manner to the tray of the preferred embodiment. 
     Side walls  22 ,  24 , and rear wall  18  are generally the same height. For reasons described hereinafter, front wall  20  is taller than the other walls and its top edge  21  is higher than top edges  23 ,  25  of side walls  22 ,  24  or top edge  19  rear wall  18 . 
     FIGS. 4-6 show a sleeve  30  comprising a sleeve top  32  having a top face  34  and a bottom face  36 , first and second side walls  38  each having an upper sidewall portion  40  and a lower sidewall portion  42  separated by a fold line  44 , and a sleeve bottom  46  comprising side wall extensions  48  glued together beneath sleeve top  32 . Sleeve top  32  is generally the same shape as, but somewhat larger than tray bottom  12 , and in fact is just large enough to cover the top opening of tray  10  defined by top edges  19 ,  21 ,  23  and  25  of the tray sidewalls. Sleeve  30  further includes a front opening  50  defined by sleeve top  32 , sidewalls  38  and sleeve bottom  46 , and a rear opening defined by the sleeve top and side walls. The presence of the fold lines  44  on the sleeve side walls makes the sleeve collapsible and permits the sleeve to be stored in a substantially flat configuration with the bottom face  36  of sleeve top  32  resting on the top of sleeve bottom  46 . 
     As can be seen in FIG. 5, the sleeve bottom is smaller that the sleeve top and is located only in the area of sleeve front opening  50 . Wall extensions  48  which form the sleeve bottom have angled back edge  52  starting at side edges  38  and converging in the direction of front opening  50  and meeting at a point  54 . This arrangement could be described as a V-shaped notch in the bottom wall of the sleeve. While a sleeve with a bottom wall comparable in size to sleeve top wall could be used, the preferred arrangement minimizes the amount of paperboard required to make the sleeve and still provides an effective product. When sleeve top  32  is generally parallel to sleeve bottom  46 , the distance between bottom wall  46  and bottom  36  of sleeve top  32  is about equal to the height of the tray side walls and is less than the height of tray front wall  20 . 
     The operation of the tray and sleeve will now be described with reference to FIGS. 7-9. In use, a tray  10  is removed from a nested stack of similar trays and an item of food, such as a slice of pizza or pie is place therein. A sleeve  30  is then erected by squeezing the fold lines  44  of the sidewalls together or by inserting a user&#39;s hand between sleeve bottom and sleeve top. While holding the sleeve in one hand and the tray in the other, tray front wall  20  is positioned under sleeve top  32  and brought to a location near meeting point  54  of the angled edge portions  52  of sleeve bottom  46 . This is shown in FIG.  7 . Since tray front wall  20  is taller than the distance separating sleeve bottom from sleeve top, top edge  21  of front wall  20  deforms the top of sleeve  30  when the tray is inserted further into the sleeve. This can seen in FIG.  8 . The paperboard material from which the container is formed and the presence of the fold line  44  in the side walls  38  allows the sleeve to deform sufficiently to allow the passage of the tray front wall through the sleeve. Alternately, or in addition, the top of the tray front wall may be somewhat flexible to facilitate its passage through the sleeve. As tray front wall  20  exits through sleeve front opening  50 , sleeve top wall  32  flexes back to a position generally parallel to the sleeve bottom wall as shown in FIG.  9 . At this point sleeve top wall  32  substantially covers tray  10  to completely enclose the food items therein and is parallel to bottom wall  46 . Because front wall  20  is taller than the height of opening  50 , the tray is effectively prevented from sliding out of the sleeve and is locked in place by the portion of the tray front wall extending above sleeve top wall  32 . 
     The sizes of tray  10  and sleeve  30  are selected such that motion of the tray into the sleeve is stopped by the sidewalls  22 ,  24  coming into contact with sleeve side walls  38  immediately after tray front wall  20  passes through sleeve front opening  50 . This locked position is also shown in FIG. 10. A user can remove the tray from the sleeve by pinching sidewalls  44  together and/or by flexing the sleeve top wall  32  away from the tray to temporarily enlarge front opening  50  enough to accommodate tray front wall  20 . 
     FIG. 11 shows a blank  100  for forming the tray of the subject invention while FIG. 12 shows a blank  110  for forming the above-described sleeve. 
     The present invention has been described herein with reference to a preferred embodiment. However, obvious modifications and additions to this embodiment will become apparent to those skilled in the art upon a reading and understanding of this specification. For example, the width of the front wall of the tray could be reduced or increased without departing from the idea of this invention. It is the applicant&#39;s intention that all such obvious modifications comprise a part of this invention to the extent that they are included within the scope of several claims appended hereto.