Abstract:
An articulable food container. The food container is articulable from and between a first open position to a second closed position. In the first open position the food container can receive food. Additionally, the user may eat from the food container while it is in the first open position. In the second closed position, the food container covers or encloses the food. The closed position is useful for storing the food, heating the food, transporting the food between the point of service and the point of consumption, and/or disposing of the remnants of the food once the meal is completed. The food container may take the form of a plate, bowl, tray, clam shell, or other known configurations.

Description:
FIELD OF THE INVENTION 
     This invention relates to food containers, particularly a food container which may be disposable, and more particularly a food container which, in use, can assume two positions—a first position for receiving food, etc., and a second position for enclosing the contents of the container. 
     BACKGROUND OF THE INVENTION 
     Disposable food containers are well known in the art. Disposable food containers include common paper plates, bowls, clam shells, trays, etc. 
     The art has paid considerable attention to making, molding, and deforming these food containers out of a single plane. In this latter process a blank is provided. The blank may have radial grooves at its peripheral region. The blank is inserted between mating dyes and pressed. The radial grooves provide for accumulation of the material deformed by the dies. Exemplary art includes U.S. Pat. Nos. 3,033,434, issued May 8, 1962 to Carson; 4,026,458, issued May 31, 1977 to Morris et al., the disclosures of which are incorporated herein by reference; 4,606,496, issued Aug. 19, 1986 to Marx et al.; 4,609,140, issued Sep. 2, 1986 to van Handel et al.; 4,721,500, issued Jan. 26, 1988 to van Handel et al.; 5,230,939, issued Jul. 27, 1993 to Baum; 5,326,020, issued Jul. 5, 1994 to Cheshire et al. However, none of these attempts in the art provide a way to use the articles described therein in a configuration other than that originally provided. Typically the articles, such as food containers, are provided in a generally open configuration with sloped side walls. The sloped side walls reduce the occurrences of food spilling from the food container. 
     Often the user would enjoy the convenience of a food container which can be open to receive food, and to eat the food placed on or in the container. At other times, the user would appreciate a container which can cover or otherwise enclose the food. Covering the food is useful in a variety of situations. For example, if the food is to be cooked (or even heated) in a microwave oven, covering, or preferably enclosing, the food reduces splattering and controls moisture loss. The user may wish to cover the food to keep it warm during the time between cooking and eating. The user may also wish to cover the food while transporting it, as may occur when food is prepared and/or served at a first location and eaten at a second location. 
     One attempt in the art to provide these conveniences is to provide a clam shell. A clam shell is a container and lid hingedly connected together. The container and lid mating surfaces are preferably symmetric about the hinge line and may have a locking mechanism to hold the lid/container combination in the closed position. Clam shells are typically used in fast food restaurants for serving hamburgers, chicken nuggets, etc. However, the use of clam shells has drawbacks. For example, clam shells are typically small, approximating the size of a hamburger. If one wishes to have an entire plate of food, the clam shell would have to be sized to accommodate. This would require a food container and lid of equal size, so that the lid could cover the food. However, this arrangement represents wasted material. Typically one does not need or wish to cover the entire plate of food at once. For example, certain foods may later be added to the food container without heating. The full sized lid/container combination of the clam shell is unnecessary. Exemplary clam shells are shown in U.S. Pat. No. 4,778,439, issued Oct. 18, 1988 to Alexander; U.S. Pat. No. 5,205,476, issued Apr. 27, 1993 to Sorenson; and U.S. Pat. No. 5,577,989, issued Nov. 29, 1996 to Neary, the disclosures of which are incorporated herein by reference. 
     Accordingly, it is an object of this invention to provide a food container which can be used in two different positions. It is further an object of this invention to provide a food container which can be used in a first open position for receiving food, and a second closed position for covering the food or remnants thereof Finally, it is an object of this invention to provide a food container which is stable in two different positions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a food container according to the present invention, the food container being in an open position. 
     FIG. 2 is an instantaneous vertical section view of the food container of FIG. 1 in a closed position. 
     FIG. 3 is an instantaneous vertical sectional view taken along lines  3 — 3  of FIG.  1  and showing the fastening devices behind the cutting plane. 
     FIG. 4 is an instantaneous vertical sectional view of the food container of FIGS. 1-3 shown in an intermediate position, between the open and closed positions. 
     FIGS. 5-6 are instantaneous vertical sectional views of asymmetric embodiments of two food containers suitable for use with the present invention, the cutting plane having been taken generally parallel to the spinal hinge lines, the embodiment of FIG. 5 having a central region with two different depths and a peripheral region of negligible radial width and the embodiment of FIG. 6 having an upstanding partition therein. 
     FIG. 7 is a top plan view of a food container according to the present invention, the food container being in an open position and having the spine offset relative to a diameter of the food container. 
     FIG. 8 is a vertical sectional view of the food container of FIG. 7 in a closed position. 
     FIG. 9 is a top plan view of a food container according to the present invention, the food container being in an open position and having the common points centered on a diameter of the food container but the spine width offset relative to the diameter. 
     FIG. 10 is a vertical sectional view of the food container of FIG. 9 in a closed position. 
     FIG. 11 is a top plan view of a food container having different major and minor axis, and being articulable about both axes. 
     FIGS. 12A and 12B are fragmentary schematic representations of a top plan view and a vertical sectional view, respectively, showing the correspondence and instantaneous angles between the transition region and peripheral region of a food container as it deviates in the Z-direction from the horizontal in FIG.  12 B and the spinal hinge lines as they converge and diverge in FIG.  12 A. 
     SUMMARY OF THE INVENTION 
     The invention comprises a food container. The food container is articulable about a plurality of multi-planar hinge lines. The hinge lines divide the container into an inboard spine and outboard wings. Preferably each wing is an isomere of the other, although, asymmetric food containers are contemplated. 
     In another execution, the invention comprises a bi-stable food container. The food container is transformable between two positions, a first open position wherein the food container can receive food and a second closed position wherein the food container covers the food. The food container has a central region and a circumjacent peripheral region. The peripheral region is raised relative to the central region when the food container is in its normal position. 
     In another embodiment, the invention comprises a method of using a disposable food container for preparing or eating food therefrom. The method comprises the steps of providing a food container having an open position for receiving food and a closed position for covering the food. Food is deposited on the food container while in the open position. The food container is closed to cover the food on the food container. While enclosed, the food container can be used to store, heat or dispose of the food. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1-3, the food container  10  according to the present invention may comprise a relatively shallow plate, a bowl, a tray, a clam shell, or any other configuration known in the art. 
     The food container  10  is articulable between a first open position and a second closed position. In the first open position the central region  14  of the food container  10  according to the present invention may be macroscopically monoplanar and accessible for food to be deposited thereon. In the second closed position, the food container  10  has a smaller footprint, and covers or even encloses the food or remnants thereof. The first and second positions are defined by structural features of the food container  10 . The first and second positions do not occur randomly or by accident as for example, may occur when a paper plate according to the prior art is crumpled for disposal. 
     The food container  10  according to the present invention is considered to be bistable. By “bistable” it is meant that the food container  10  can indefinitely remain in either the first or second position. The food container  10  does not move from the first position to the second, from the second position to the first or from either position to an intermediate position without external influence. Nor does the food container  10  assume other positions or configurations as illustrated in FIG. 4 without external influence. Furthermore, the food container  10  enjoys unexpected rigidity while in the first position. 
     Examining the food container  10  of FIGS. 1-3 in more detail, the food container  10  comprises a central region  14  and a circumjacent peripheral region  16 . The central region  14  and peripheral region  16  are disposed in two different planes. The central region  14  defines the X-Y plane of the food container  10 . The Z-direction of the food container  10  lies perpendicular to the X-Y plane. Of course, one of ordinary skill will recognize the food container  10  will necessarily contain a transition region from the central region  14  to the peripheral region  16 . In normal use, the peripheral region  16  is typically raised relative to the central region  14 . The peripheral region  16  is joined thereto at a non-perpendicular angle. 
     The boundary and shape of the peripheral region  16  are defined by the edge  18  of the food container  10 . It is to be recognized that the dimensions and relative proportions of the peripheral region  16  and central region  14  of the food container  10  will vary according to the exact size and intended use of the food container  10 . While a round food container  10  is illustrated in FIG. 1, one of ordinary skill will recognize that any suitable shape and depth of food container  10  may be selected for use with the present invention and the invention is not so limited. Other suitable shapes include squares, rectangles, ovals, various polygons, etc. 
     It is not necessary that either the central region  14  or the peripheral region  16  be flat, parallel to the X-Y plane, or be generally planar. One of ordinary skill will recognize that, for example, bowls having a generally concave shaped bottom will be suitable for use with the present invention. It is only necessary that the central region  14  and the peripheral region  16  be spaced apart in the Z-direction. The Z-direction distance from the bottom surface of the central region  14  (taken while the food container  10  is in its normal in-use and open, generally horizontal position) to the top surface of the peripheral region  16  is referred to as the Z-direction depth  19  of the food container  10 . If there are different Z-direction depths  19  at different portions of the food container  10 , the Z-direction depth  19  is taken at the vertices  50 , discussed below, of the spinal hinge lines  20 . It is to be recognized that different vertices  50  may define different Z-direction depths  19 . FIG. 5 illustrates a food container having dual Z-direction depths  19 . 
     Referring back to FIG. 3, the food container  10  according to present invention is divided by a plurality of, and preferably two, hinge lines  20 . A preferred configuration has spaced apart first and second hinge lines  20 , referred to as spinal hinge lines  20 . 
     The spinal hinge lines  20  divide the food container  10  into two wings  22 , and a spine  24  disposed between the wings  22 . The wings  22  are outboard of the spine  24 . Ordinarily each wing  22  is an isomere of the other. However, it is to be recognized that asymmetrical configurations may be desirable and are within the scope of the claimed invention as shown in FIGS. 5-10. 
     The spinal hinge lines  20  allow the wings  22  to be articulated about either spinal hinge line  20 . Preferably the articulation is reversible and more preferably sustainable for a number of cycles, so that the food container  10  may be opened and closed a number of times. 
     Both portions of the food container  10 , i.e., the wings  22  and the spine  24 , may be articulated about the spinal hinge line  20 . Of course, the articulation is in a direction generally perpendicular to the spinal hinge lines  20 . 
     Preferably the spinal hinge lines  20  are generally parallel and symmetrical with one another. However, it is to be recognized that the spinal hinge lines  20  may be slightly concave towards each other or slightly convex away form each other or a combination thereof. If a clam shell is selected for the food container  10 , the spinal hinge lines  20  should be generally perpendicular to the hinge of the clam shell. 
     Referring back to FIGS. 1 and 2 and examining the spine  24  in more detail, the spine  24  has a width  26 , taken generally perpendicular to the principal direction of the spinal hinge lines  20 . If the spinal hinge lines  20  are not straight, the width  26  of the spine  24  is taken directly perpendicular to the spinal hinge lines  20  at the point(s) where the spinal hinge lines  20  intercept the peripheral region  16 . The width  26  of the spine  24  is measured along this perpendicular, from the centerline of the first spinal hinge line  20  to the centerline of the second spinal hinge line  20  along the outer surfaces of the food container  10  while it is in the closed position of FIG.  2 . 
     The width  26  of the spine  24  is important to providing the bistable characteristics of the food container  10 . Preferably, the width  26  of the spine  24  is approximately two times the Z-dimension depth  19  from the central region  14  to the peripheral region  16 , taken at the vertices  50  described above. By proportioning the width  26  of the spine  24  to be approximately two times the Z-dimension depth  19 , the food container  10  can remain in the closed position without undue stress or being unstable. The spine width  26  will be tapered if the Z-direction depth  19  varies between the diametrically opposed vertices  50 . 
     Referring to FIGS. 7-8, it is not necessary that the spine  24  be centered on the food container  10  or centered on a diameter D of a round food container  10 . For example, the spine  24  may be offset relative to the diameter D of a round food container. Such configurations are feasible and within the scope of the claimed invention. This arrangement allows for partial covering of the contents of the food container. This embodiment may be useful where increased venting or contact between the contents and the atmosphere is desired. 
     Referring to FIGS. 9-10, the common points  30  of the spine  24  may also be centered on a diameter D, with the spinal hinges line  20  unequally spaced, in the width direction, from this diameter. In this configuration, the common points  30  are diametrically opposed, unlike the embodiments of FIGS. 7-8 where the common points  30  lie on a chord. In the embodiment of FIGS. 9-10, the wings  22  will not be isomeres of one another. Instead, one wing  22  will be shorter, in the width direction, than the other wing  22 . However, it is to be recognized as illustrated in FIG. 10 that when the food container  10  is articulated to the closed position, the spine  24  will not be perpendicular to the wings  22 . Instead, the spine  24  will be disposed in a non-perpendicular relationship relative to the wings  22 . 
     Referring to FIGS. 1,  7 , and  9 , as the spinal hinge lines  20  approach the peripheral region  16  of the food container  10 , the spinal hinge lines  20  may converge towards one another. Upon convergence, the spinal hinge lines  20  intercept each other at a common point  30  juxtaposed with the peripheral region  16  of the food container  10 . Preferably the common point  30  is coincident the highest Z-direction elevation of the peripheral region  16 . 
     Referring to FIGS. 12A and 12B, the hinge lines  20  may converge towards this common point  30  at a predetermined azithmuthal angle  32 A. The instantaneous azithmuthal angle  32 A measured as the included angle between the spinal hinge lines  20 , is nominally equivalent to two times the instantaneous angle  32 B taken in the Z-direction, at which the peripheral region  16  of the food container  10  rises from the central region  14  of the food container  10 . 
     Referring to FIGS. 1,  7 ,  9 ,  11 , and  12 A the spinal hinge lines  20  may be provided by any means well known in the art. Preferably, the spinal hinge lines  20  comprise lines of weakness, reducing the bending force across that hinge line  20  and allowing the food container  10  to fold in a predetermined manner. The spinal hinge lines  20  may be disposed on the tension side  36  or the compression side  38  of the food container  10 . Suitable spinal hinge lines  20  include score lines, and perforations if the intended use does not involve liquids. Material can be cut or removed from the food container  10  to form the spinal hinge lines  20 . Preferably, however, material is compressed or densified to form the spinal hinge lines  20 . Scoring design and techniques are well known in the art. 
     The spinal hinge lines  20  according to the present invention are considered to the multi-planar. By “multi-planar” it is meant that the spinal hinge lines  20  traverse a single direction, and extend, at least for a discernible distance, in a direction having a vector component perpendicular to the first direction. 
     Preferably, the point at which the spinal hinge lines  20  deviate from the first direction is coincident a topographical or structural feature of the food container  10 . As illustrated in the figures the spinal hinge lines  20  generally deviate from planarity at the points where the spinal hinge lines  20  intercept the peripheral region  16  of the food container  10 . 
     At these points, one or more connector hinge lines  40  having a principal direction generally perpendicular to the spinal hinge lines  20  may be provided. Preferably two such connector hinge lines  40  are provided and are diametrically opposite the center of the food container  10 , as illustrated in FIG.  1 . The connector hinge lines  40  may be juxtaposed with and approximate the inwardly disposed portion of the peripheral region  16  of the food container  10 . Preferably, the connector hinge lines  40  are congruent thereto and therefore, may subtend an arc equivalent to the width  26  of the spine  24 . 
     The connector hinge lines  40  intercept the spinal hinge lines  20  at two vertices  50 . The vertices  50  are disposed on the radially outermost portion of the central region  14 , and coincident the Z-direction elevation of the central region  14 . The two vertices  50  and their respective common point  30  (where the spinal hinge lines  20  intercept one another) form a generally triangular panel  52 . Without being bound by theory, it is believed the triangular panel  52  may inflect from a concave inward position to a concave outward position and assist the food container  10  in remaining in the first and second positions. However it has been found that the existence of material in the triangular panels  52  is not critical to the claimed invention, although its absence will allow leakage. 
     The food container  10  according to the present invention may be made of a rigid material, particularly a material which provides for inflection of triangular panel  52 , as noted above. Suitable rigid materials include foam, plastic, and various other synthetic materials. The food container  10  may be made of cellulose and, if so, may be made of solid bleached sulfite or layers of various types of fibers including recycled cellulose. If desired, additional rigidity and thermal insulating capability may be provided by the materials selected for the food container  10 . For example, the food container  10  may be made of corrugated board. 
     Corrugated board comprises a generally flat layer, and a corrugated layer. The corrugated layer is not joined at all positions to the flat layer, but instead has ribs which are spaced apart from the flat layer and troughs joined to the flat layer. The ribs and troughs are often straight and parallel, but may be sinusoidal. In cross section, a rib may be S-shaped, C-shaped, Z-shaped, or have any other configuration known in the art. Furthermore, if desired, a second flat panel may be joined to the corrugated medium and disposed oppositely from the first flat panel. 
     The food container  10  may be molded from a pulp slurry or pressed from a blank between mating plate-shaped platens. Both methods of manufacture are well known in the art. 
     If desired one or more fastening devices  60  may be added to the food container  10  to assist in maintaining the food container  10  in the closed second position. Fastening devices  60  are well known in the art. For the embodiment described herein, having a generally round shape two fastening devices  60  may be provided on the food container  10 . The fastening devices  60  may be disposed at positions subtending an included angle of 60° or greater. For the embodiments described herein, a 90° included angle allows the fastening devices  60  to be positioned midway between the common points  30  and the point on the edge  18  of the food container  10  furthest from the spine  24  when the food container  10  is in the closed position. 
     Suitable fastening devices  60  include those having two complementary portions which are peripherally spaced apart, and preferably oppositely disposed. One portion is disposed on each isomere of the food container  10 . Suitable fastening devices  60  include pressure sensitive adhesive, selectively activatable adhesive, hook and loop fasteners, tab and slot fasteners, and cohesive fasteners. Selectively activatable adhesive may be used if one wishes to completely seal the food container  10  according to the present invention for relatively long term food storage. The fastening devices  60  may be made generally in accordance with commonly assigned U.S. Pat. Nos. 4,979,613 issued Dec. 25, 1990 to McLaughlin et al.; 5,230,851 issued Jul. 27, 1993 to Thomas; or 5,662,758 issued Sep. 2, 1997 to Hamilton et al., the disclosures of which are incorporated herein by reference. If desired embossed and deformable mating snap fasteners wherein one wing of the food container  10  locks or mechanically latches into the other wing of the food container  10  may be utilized. 
     While disposable food containers  10  have been described above, it is to be recognized that durable and reusable food containers are within the scope of the claimed invention as well. Additionally, the materials from which the food container  10  are made need not be the same throughout. For example, the spine  24  of the food container  10  may be made of a heavier material than the wings  22 . Also, one wing  22  may be longer, heavier or differently shaped than the other wing  22  if, for example, it is desired to have the second wing  22  serve primarily as a lid for the first wing  22 . Also, the wings  22  need not be isomeres of each other. Asymmetrical configurations (as taken both parallel and perpendicular to the spine  24 ) as illustrated in FIGS. 5-10, are within the scope of the claimed invention as well. Additionally, the food container  10  may comprise an upstanding partition, as illustrated in FIG. 6, to provide separate compartments within the food container  10 . The upstanding partition may intercept the spinal hinge lines  20 . 
     The food container  10  may be executed in a variety of configurations and geometries. However, one of ordinary skill will recognize there are practical limits to the possible geometries. For example, as the radius of the central region  14  approaches the Z-direction depth  19  of the food container  10 , the volume of the food container  10  will be limited when it is in the closed position. 
     Furthermore, the peripheral region  16  of each wing  22  of the food container  10  need not be in registry with the peripheral region  16  of the other wing  22  when the food container  10  is in the closed position. Although such embodiments are illustrated one of ordinary skill will recognize that a food container  10  having the peripheries  16  of the wings  22  offset from one another in the closed position may also be desirable as illustrated in FIG.  8 . Such a configuration allows for venting of steam, etc., during cooking. 
     Referring to FIG. 11, the food container  10  of the present invention is suitable for use with elliptical and other non-aximmetrically shaped food containers  10 . For example, the food container  10  may have unequal major and minor axes A, I. In such a configuration, a spine  24  and spinal hinge lines  20  may be provided in the two mutually perpendicular directions coincident the major and minor axes A, I. Of course, one will recognize that a spine  24  and spinal hinge lines  20  may be provided in a direction intermediate the major axis A and minor axis I of the food container  10 . The embodiment of FIG. 11 provides the advantage that, depending upon the direction selected for articulation from the open position to the closed position, the food container  10  may have different aspect ratios in the closed position. Thus, contents of different shapes may be readily accommodated by the food container  10 . Also, a round food container  10  may be provided with plural spines  24  and associated spiral hinge lines  20 . 
     Many other combinations and variations are feasible and within the scope of the appended claims. 
     REFERENCE NUMERALS 
       10  food container 
       14  central region 
       16  peripheral region 
       18  edge 
       19  Z-direction depth 
       20  spinal hinge lines 
       22  wings 
       24  spine 
       26  width 
       30  common point 
       32 A azithmuthal angle 
       32 B instantaneous vertical angle 
       36  tension side 
       38  compression side 
       40  connector hinge lines 
       50  vertices 
       52  triangular panel 
       60  fastening device 
     D diameter 
     A major axis 
     I minor axis