Patent Publication Number: US-7712626-B2

Title: Edge-tearing tamper evident container

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation application of U.S. patent application Ser. No. 11/496,215, filed 31 Jul. 2006, which is a continuation-in-part of U.S. patent application Ser. No. 11/166,308, filed 24 Jun. 2005, each of which are incorporated by reference herein in their entireties. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention generally relates to containers, and in particular to tamper-evident containers. 
     2. Description of the Related Art 
     Food is often placed in a transparent plastic container that includes a base with a large volume cavity that holds the food and with a cover or lid that closes the cavity. Buyers want to be assured that, after the food was placed in the container as by a clerk at the food store, that the container has not been opened. There is a possibility that another customer has secretly opened the container enough to taste a bit of food before closing it (and possibly leaving germs from his/her finger in the food). Potential buyers want to be assured that this has not happened. A container that could be constructed at low cost from plastic, that could be easily initially closed by a clerk at a store after loading goods such as food into the container, and which thereafter required a customer to tear apart parts of the container before initially opening it, would be of value. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the invention, a container is provided that can be constructed at low cost, that can be loaded with goods and initially closed by a clerk at a store, and that thereafter requires a customer to manipulate the container when initially opening it, in a manner that makes it clear that the container was initially opened. The container is constructed of plastic, and preferably of a sheet of plastic that has been formed into the shape of a base having an upwardly-opening cavity for holding goods, and a lid that can close the cavity. The base and lid initially have adjacent first sides and widely-spaced second sides. The first sides are joined by a join line in the plastic sheet that can be easily torn. At the join line, the base and lid have been bent and the bend has been creased, so rim portions of the base and lid lie facewise adjacent to each other. A bump is formed in one of the rim portions to slightly separate the base and lid rim portions. 
     A clerk loads food into the cavity of the base, and moves the second sides of the container together so they latch together. The second sides latch together to close the container, in a manner that prevents their initial separation. With the second sides of the base and lid latched together and the first sides joined along a join line that must be torn to separate the first sides, the container is securely initially closed. In this condition, the goods in the container cannot be readily touched or sampled by a customer. For a buyer of the container to initially open the container, the buyer must tear apart the first sides of the base and lid along the join line. The join line is weakened, as by a series of slits, so it can be more easily torn apart. 
     The first sides of the base and lid are formed with a tab in the lid that can be pulled up to tear the join line while the base is held down. The base can be held down by a person grasping a base tab that is horizontally spaced from the lid tab. The outer end of the lid tab, which lies furthest from the container vertical axis, is formed out of material in a flat rim of the first side of the base, to thereby leave a cutout in the base under the lid tab. 
     The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top and rear isometric view of a container of a first embodiment of the invention in its initially closed position. 
         FIG. 2  is a view similar to that of  FIG. 1 , but showing a person initially opening the container. 
         FIG. 3  is a top and rear isometric view of the container of  FIG. 1 , showing the container prior to its initial closing, and with the lid raised. 
         FIG. 4  is top and rear isometric view of the container of  FIG. 3 , with the lid in its fully open position prior to its initial closing, and showing the container as its is initially vacuum formed. 
         FIG. 5  is a sectional view taken on line  5 - 5  of  FIG. 1 . 
         FIG. 6  is an enlarged isometric view of a portion of the container of  FIG. 3 . 
         FIG. 7  a partial isometric view of a first side of a container of another embodiment of the invention, wherein base and lid tabs lie on opposite sides of a join line, with the container in its initially closed position. 
         FIG. 8  is a view similar to that of  FIG. 7 , but with the container in the configuration it achieves after an initial opening. 
         FIG. 9  is a partial isometric view of a first side of a container of another embodiment of the invention, wherein the base and lid tabs lie at opposite corners of the first side of the container, with the container in its initially closed position. 
         FIG. 10  is a view similar to that of  FIG. 9 , but with the container in the configuration it achieves after an initial opening. 
         FIG. 11  is a partial isometric view of a container of another embodiment of the invention, which has a lid tab but no base tab. 
         FIG. 12  is a sectional view taken on line  12 - 12  of  FIG. 11 . 
         FIG. 13  is a partial isometric view of a container of another embodiment of the invention which is similar to  FIG. 9 , but with the base and lid tabs at the same corner of the container. 
         FIG. 14  is a view similar to  FIG. 13  after an initial container opening. 
         FIG. 15  is a view of a container similar to that of  FIG. 13  but with base and lid tabs at each of two corners. 
         FIG. 16  is a view similar to that of  FIG. 14 , after an initial container opening. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates a container  10  of the present invention, which includes a base  12  with an upwardly-opening cavity  14  for holding goods such as food, and a lid  16  that closes the top of the cavity. The base and lid of  FIG. 1  are preferably formed of a single sheet of plastic that has been thermoformed as by vacuum forming, transfer molding or blow molding. It is even possible to injection mold the container to form a container comprising a plastic sheet. The base and lid have second sides  20 ,  22  that are securely held to each other so the second sides cannot be separated until after first sides  24 ,  26  have been separated. The first sides  24 ,  26  of the base and lid are initially fixed together along a join line  30  formed in an integral portion of the plastic sheet, that can be easily torn. Along the first sides, the lid has a lid tab  32  that projects radially outward with respect to the container vertical axis  34  and the base has a projecting base tab  36 . As shown in  FIG. 2 , the container can be initially opened by a person grasping the lid tab  32  between the thumb and index fingers of a first hand A and lifting the lid tab. At the same time, the person can hold down the base by grasping the base tab  36  between the thumb and index fingers of the person&#39;s other hand B. Such lifting causes the lid and base to tear apart along the join line  30 . The join line can be straight or curved or jagged. 
       FIGS. 3 and 4  show the container  10  as it is supplied to a store, and before a store clerk has loaded goods into the container and initially closed the container. The first sides  24 ,  26  of the base and lid are joined along the join line  30 , but the second sides  20 ,  22  are separated. The base and lid are in the form of thin plastic or plastic sheeting, and preferably are parts of the same sheet of plastic (which may have portions of different thickness). The join line is formed in an integral sheet of plastic.  FIG. 4  shows the container as it is initially formed from a single sheet of thermoformed plastic which has been thermoformed to the illustrated shape, and with slits cut along the join line  30 . The lid is folded or bent 180 degrees from  FIG. 4  to achieve the initially closed position of  FIGS. 1 and 2 . 
       FIG. 6  shows the first sides of the base and lid, showing that the join line  30  includes opposite join line parts  30 A and  30 B that lie on opposite sides of the lid and base tabs  32 ,  36 . Along each join line part there are four join lengths  40  and an interrupted slit  42  with slit parts  43 . Applicant prefers to provide join lengths  40  each of no more than 0.25 inch length. Leading to each join line part  30 A,  30 B is an entrance slit  44  of an end width of the same order of magnitude as the slit  42 , that leads from the tabs  32 ,  36  to the join line parts, to concentrate separation forces along the join line parts. In addition, the plastic sheet has been creased (by forming a sharp bend such as a bend having a radius of curvature no more than the thickness of the two sheet portions being bent) to weaken it along the join line. 
     It can be seen in  FIG. 6  that the lid tab  32  has a radially outward O extension  52  that projects beyond the join line  30 , and that the base has a cutout  50  initially lying around the lid extension (when the lid is pivoted 180 degrees from its closed position). The base tab  36  has a similar extension  54  and the lid forms a cutout around it. This provides longer tabs that can be more easily grasped and cutouts under or over the tabs.  FIG. 6  also shows that the first sides of the base and lid form join rim parts  60 ,  62  that are each flat and that lie facewise adjacent to each other when the lid is closed on the base. The rim part  60  of the base has bumps  64  that assure slight separation of the rim portions after the join line is torn. 
     A clerk at a store receives a stack of containers in the configuration shown in  FIG. 4 , with the first sides  24 ,  26  of the base and lid joined and with the second sides  20 ,  22  widely separated. The clerk first loads goods such as food into the cavity  14  of the base, and then pivots the lid so its second side lies over the base second side. The clerk then forces the lid second side downward to lock, or latch it to the base second side, to place the container in an initially closed configuration.  FIGS. 1 and 2  show the container in such initially closed configuration. 
       FIG. 5  shows the first and second sides of the base and lid after the lid has been initially closed on the base. The second side  20  of the base has a free rim  70  with a downwardly-facing shoulder  72 , and the second side  22  of the lid has a free rim  74  with an upwardly-facing shoulder  76  that abuts the base shoulder  72  to latch the container second side closed. The base and rim also have sealing surfaces  80 ,  82  that abut to prevent the leakage of liquids and that keep the lid closed after the initial opening but allow opening with a small force such as less than one pound. When the clerk presses down the lid on the base during initial closing of the container, the lid moves down until stopped by a lid limit surface  84  abutting the base limit surface  86 , and the lid moves up slightly to its final closed position shown in  FIG. 5 . In that position, the shoulder  76  on the lid free rim  74  abuts the base shoulder  72  to thereafter prevent the lid second side from being lifted while allowing the lid to be pivoted. The same lid and base sealing surfaces and shoulders extend around the entire container, except that the shoulders  72 ,  76  are not present below the portion of the first side of the base and lid that lies below the join line and the tabs. 
     It would be possible to fix the second sides of the lid and base to each other in a true pivot joint, as by sonically welding the top and bottom of a strip of flexible sheet plastic material to the base and lid, although that is not necessary.  FIG. 5  shows that the flat rim parts  60 ,  62  that lie along the joining line  30 , lie facewise adjacent to each other with only the bumps  64  separating them, and also shows the crease line  78 . 
     There are no tabs or other projections at the lid second side  20  that can be grasped to pull it up. Accordingly, after the clerk has initially closed the lid on the base, the only way for a customer to open the container is for the customer to tear the plastic sheet along the join line  30 , as by forcefully lifting the lid tab  32  while holding down the base (as by holding the base tab  36 ). When the customer tears the plastic sheet along the join line, he/she thereafter can easily close the container, and can reopen the container by lifting the lift tab  32  with a small force (e.g. less than one pound). When the first side of the container is opened by lifting the lid tab  32 , the second side of the lid can slide slightly towards the first side so the lid shoulder  74  does not lie under the base shoulder and therefore the lid can be easily completely separated from the base. 
       FIG. 7  shows another embodiment of the invention wherein the base and lid tabs  90 ,  92  lie on opposite sides of an uninterrupted join line  94 . In  FIG. 7  the join line  94  has not been torn, while  FIG. 8  shows the join line torn as a result of an initial opening of the container.  FIGS. 5 and 10 , show another embodiment of the invention wherein the base and lid tabs  100 ,  102  lie at corners of a container of rectangular shape (as seen in a plan view), at opposite ends of the first side of the container. 
       FIG. 13  shows another container wherein the base and lid tabs  130 ,  132  lie one above the other, and at a corner of a container. In  FIG. 14  the join line  134  has been torn as a result of an initial opening, and the lid tab has been bent to extend at an upward incline.  FIG. 15  shows a pair of base and lid tabs  140 ,  142 ,  144 , 146  at opposite ends of a join line  150 .  FIG. 16  shows the container of  FIG. 15  after the lid tabs have been pulled up and the join line has been torn. 
       FIG. 11  shows a portion of a base  110  and lid  112  of a round (of circular or oval configuration as seen in a plan view) container, with only a lid tab  114  between opposite portion  120 ,  122  of a join line  124 . A person grasps the base with one hand while lifting the lid tab  114  with the other hand to tear the join line to initially open the container (that is, to first open the container after it was initially closed). 
     The container can be formed from a wide variety of polymers, including polystyrene, polypropylene, polyethylene terephthate, etc. Instead of a container of primarily rectangular shape as illustrated in a plan view, the container may be circular, elliptical, or of any reasonable polygonal shape. The base (and cover) can have walls forming compartments, and the container can include a middle tray. 
     Thus, the invention provides a container comprising a base and lid that can be constructed at low cost, that can be shipped to a store with its cavity open to enable easy loading of food or other goods by a store clerk, and that can be easily closed by the store clerk. The base and lid are preferably formed of a single sheet of plastic, and are joined by a join line that can be torn. After initial closing by the store clerk, the container strongly resists initial opening, to greatly discourage customers from secretly opening the container as to taste food in it. Instead, initial opening requires forceful opening by lifting a tab on the lid to tear the plastic sheet along the join line. Once the container has been initially opened, the fact that it has been initially opened is evident to anyone who looks at the container, which assures buyers that the container is intact. The container thereafter can be easily opened and closed. The plastic sheet that forms the container has a crease along the tear line, and has a narrow slit leading to the tear line. The lid tab extends axially outward beyond the join line by leaving a cutout when it is formed in the plastic sheet. 
     Although particular embodiments of the invention have been described and illustrated herein, it is recognized that modifications and variations may readily occur to those skilled in the art, and consequently, it is intended that the claims be interpreted to cover such modifications and equivalents.