Abstract:
A thermoformed thermoplastic container has a lid which closes on a base in a snap fit. A signal tab is hinged to the base and has a tubular projection which folds over the lid and is received in a friction fit with a downwardly extending lid projection. After the container is filled with product, the signal tab is pressed into place on the lid and lies flat. In order to open the lid the signal tab is pulled up, thereby severing a perforated line extending around the lid projection, and separating the lid projection from the lid which prevents the signal tab from again engaging with the lid, thereby serving as an indicator to a customer that the package has been opened.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to reclosable containers in general, and more particularly to containers having elements which indicate that the container has been opened after its original closure. 
         [0004]    There are a number of consumer products, such as bakery or deli foods, which are placed in containers which are closed and put on display for consumer selection. This type of merchandizing can reduce retailer labor, and allows consumers to select the products they desire at their own pace. However, particularly with consumable foodstuffs, customers may seek some assurance that the products they are purchasing have not been tampered with or been pilfered by others. This can be done by applying a shrink-wrapped plastic band to the sealed container, although this requires special equipment and can unduly add cost. 
         [0005]    Containers are also known which employ press-fit connectors on the container base and lid which engage with one another when the container is closed to retain the container in a closed configuration. Weakened regions of material such as perforations are disposed such that the force necessary to open the lid causes portions of the container to be severed, either to be separated from the container or to be retained on an opposed container part. Such arrangements provide evidence of tampering either due to the absence of some package part, or due to the open condition of the container. Yet for the untrained observer, the absence of a container part may not immediately indicate tampering, and, although an open container is readily understood, customers may wish to have containers that are reclosable for retention of partial quantities of product. 
         [0006]    What is needed is an economical container that effectively presents consumer merchandise, is reclosable, and which clearly indicates that it has been opened after its initial closure. 
       SUMMARY OF THE INVENTION 
       [0007]    The container of the present invention is preferably formed of thermoformed thermoplastic material, and has a lid which closes on a base in a retention fit. A signal tab is hinged to the base and has a tubular projection which folds over the lid and is received in a friction fit with a downwardly extending lid projection. After the container is filled with product, the signal tab is pressed into place on the lid and lies flat. In order to open the lid the signal tab is pulled up, thereby severing a perforated line extending around the lid projection, and separating the lid projection from the lid which prevents the signal tab from again engaging with the lid, thereby serving as an indicator to a customer that the package has been opened. The lid may be hinged to the base, or the lid may be entirely separable from the base and multiple signal tabs may be provided on multiple sides of the container to engage with multiple lid projections. Because the signal tab plays no part in retaining the lid in its closed condition, the package may always be reclosed. 
         [0008]    It is an object of the present invention to provide a reclosable container which provides an indication of access to its interior after its original closure. 
         [0009]    It is a further object of the present invention to provide a tamper evident mechanism suitable for a wide variety of reclosable containers. 
         [0010]    Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]      FIG. 1  is an isometric view of the container of this invention in an open configuration. 
           [0012]      FIG. 2  is a fragmentary isometric view of the container of  FIG. 1  with the lid closed on the base, prior to engagement of a signal tab. 
           [0013]      FIG. 3  is a fragmentary isometric view of the container of  FIG. 2  with the signal tab closed on the lid. 
           [0014]      FIG. 4  is a fragmentary isometric view of the container of  FIG. 3  with the signal tab opened and indicating that the container&#39;s closure has been disturbed. 
           [0015]      FIG. 5  is a cross-sectional view of the container of  FIG. 1  in the process of being closed. 
           [0016]      FIG. 6  is a cross-sectional view of the container of  FIG. 3  taken along section line  6 - 6 . 
           [0017]      FIG. 7  is a cross-sectional view of the container of  FIG. 4  taken along section line  7 - 7 . 
           [0018]      FIG. 8  is an exploded isometric view of an alternative embodiment container of this invention having a lid which is fully separable from the base. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0019]    Referring more particularly to  FIGS. 1-8 , wherein like numbers refer to similar parts, a reclosable container  20  is shown in  FIGS. 1-7 . As shown in  FIG. 1 , the container  20  is preferably thermoformed from a sheet of thermoplastic material, for example transparent polyethylene terephthalate (PET). The container has a base  22  with a bottom wall  24  and an upwardly extending side wall  26  which define a container interior  28  which will receive contents such as food products. The side wall  26  extends to an upper lip  30  which has a surrounding peripheral skirt  32  which terminates in an outwardly extending terminal flange  34 . 
         [0020]    An integral hinge  36  extends from the terminal flange  34 , and a lid  38  is connected by the hinge so it may be pivoted into a closed position on the base  22 . The lid  38  has an outwardly extending flange  40  which is connected to the hinge  36 , and a peripheral skirt  42  which extends upwardly from the flange. A top wall  44  extends from the skirt  42 , such that when the lid  38  is closed on the base  22  the container interior  28  is sealed. The top wall  44  is preferably formed with an interior skirt  46  which is configured such that the peripheral skirt  42  and the interior skirt snap into engagement with the base peripheral skirt  32  and portions of the base side wall to retain the lid in a closed configuration on the base. The container  20  may thus be loaded with product and then placed on display in a retail establishment for consumer self-service. However, because the lid may be repeatedly opened and resealed on the base, a consumer will desire to know that the contents of the container have not been tampered with after the initial loading with product by the retailer. The consumer is provided with this information by a tamper-evident mechanism  48  which is integrally formed with the container  20 . 
         [0021]    The tamper-evident mechanism  48  has a signal tab  50  which is connected by an integrally formed hinge  52  to the base terminal flange  34 . The signal tab  50  has a narrow rectangular spacer element  54  which is joined by an intermediate integrally formed hinge  56  to a main element  58 . The main element  58  is formed with a tubular projection  60  which may be generally cylindrical or tapered like the frustum of a cone. 
         [0022]    The tamper-evident mechanism  48  further has a cooperating structure formed on the lid  38  of the container  20 . As shown in  FIG. 5 , the lid  38  has an upper wall  62  which extends inwardly from the peripheral skirt  42 . A lid projection  64  extends downwardly from the lid upper wall  62  and is of a size and shape to engage with the signal tab projection  60  in an interference or friction fit. For example, the lid projection  64  may be generally square in section, to engage with the frustoconical signal tab projection. 
         [0023]    The base  22  has an upper wall  66  which extends inwardly from the base peripheral skirt  32  and is positioned to directly underlie the lid upper wall  62  when the lid  38  is closed on the base. The base upper wall  66  and the lid upper wall are thus substantially parallel and in close proximity to one another when the lid is closed on the base. A relief  68  is formed in the base upper wall  66  to allow the lid projection to pass through without obstruction. The relief  68  may be a die-cut opening, but for ease of manufacturing it is formed as a downwardly extending closed projection. The relief  68  is larger than the lid projection and does not engage it. Hence when the lid  38  is closed on the base  22 , the lid projection does not hamper the snap fit seal between the lid and the base. 
         [0024]    As shown in  FIG. 2 , a region of weakened material  70  is formed in the lid upper wall  62  around the lid projection  64 . The region of weakened material  70  may be formed, for example, by a die-cut with notched segments or perforations, or by a thinning of the plastic or by other means. As shown in  FIG. 6 , the region of weakened material  70  may define, for example, a circle, which is greater in diameter than the size of the base upper wall relief  68 , such that the region of weakened material is supported on the base upper wall  66  and separation of the lid projection  64  at the region of weakened material is prevented when the lid projection  64  is pressed downwardly. It will be noted that the closed cavity of the base relief  68  serves to protect the downwardly extending lid projection from inadvertent engagement by a customer which might tend to push the projection  64  upwardly and disturb the region of weakened material  70 . 
         [0025]    Two detents  72  are formed, one on either side of the signal tab projection  60 . These detents prevent the main element  58  of the signal tab  50  from approaching so close to the base upper wall  66  so as to prevent a user from engaging the main element  58  and pulling it upwardly. The height of the detents  72  serves to maintain a narrow gap between the base upper wall  66  and the signal tab main element, so an edge of the main element can be readily engaged and manipulated. 
         [0026]    The container  20  is loaded with product while the lid  38  is opened, as shown in  FIG. 1 . The lid  38  is then closed on the base  22  as shown in  FIGS. 2 and 5 . The lid  38  has molded structure which engages the base  22  and secures the lid in a closed configuration on the base. For example, the lid outer peripheral skirt  42  and interior skirt  46  engage the base peripheral skirt  32  and side wall  26  respectively. Once closed on the base, the lid  38  may be opened and closed repeatedly. To provide a customer an indication of whether the container has been opened after its initial loading, the signal tab  50  is pivoted on the hinges  52 ,  56 , to bring the signal tab projection  60  into engagement with the lid projection  64 , as shown in  FIGS. 3 and 6 . The signal tab spacer element  54  is at least as wide as the distance the base upper wall  66  is spaced above the base terminal flange  34 . The signal tab projection  60  is dimensioned so that when it is pressed into engagement with the lid projection  64  the parts are deformed to retain the two in engagement with one another. As shown in  FIG. 3 , the lid upper wall  62  is preferably slightly relieved below the level of the surround lid top wall  44 , such that the engaged signal tab  50  does not project substantially above the top wall and provide an obstruction which might be readily engaged when handling loaded containers, for example while stacking them one on another. 
         [0027]    Once the signal tab projection  60  is secured to the lid projection  64 , the lid  38  may not be opened without first getting the signal tab  50  out of the way. However, the dimensions of the parts are such that the force required to separate the signal tab projection  60  from the lid projection  64  is greater than the force required to sever the line of weakened material  70  and separate the lid projection  64  and its surrounding portion of the lid upper wall  62  from the lid. Thus, as shown in  FIGS. 4 and 7 , when the signal tab  50  is engaged by a user and pivoted away from the lid, the discrete element  73  containing the lid projection  64  remains affixed to the signal tab, leaving a perforated opening  75  in the lid above the base relief  68 . The signal tab  50 , no longer connected to the lid, then extends away from the base  22  providing a clear signal that the container has been tampered with after its initial closure. The hinge  52  may undergo plastic deformation when the signal tab is folded into engagement with the lid, with the result that the signal tab extends vertically when released from the lid, as shown in  FIG. 7 . Although the container  20  may still be closed, the signal tab  50  can not be restored to its engagement with the lid  38 . It should be noted that the perforated opening  75  does not communicate with the container interior  28 , and hence does not compromise the seal of the container. 
         [0028]    It should be noted that although the projection on the signal tab has been illustrated as extending from the signal tab towards the lid to engage with a downwardly extending projection on the lid, it and the lid projection could also be projecting upwardly. 
         [0029]    It should be noted that, although in the  FIGS. 1-7 , the container is shown having a clamshell construction with a lid which is attached by an integral hinge to the base, the container may have an unhinged lid. An alternative embodiment container  74 , shown in  FIG. 8 , employs a lid  76  which is not hinged to the container base  78  but is entirely separable from the base. In such a configuration, the container  74  has multiple tamper-evident mechanisms  48 , at least one on multiple sides of the container, for example on two opposite sides of the lid, whereby at least one of the tamper-evident mechanisms must be disturbed to gain access to the container interior. The mechanisms  48  may be similar to the ones discussed above. 
         [0030]    It should be noted that the container lid may have a perforation along the hinge or parallel to the hinge to permit it to be separated from the base by the consumer. 
         [0031]    It should be noted that although a particular friction fit arrangement is disclosed between the signal tab projection and the lid projection, other structures which allow the engagement between the two parts may be employed, so long as the arrangement is such that the force required to separate the two parts is greater than the force required to sever the region of weakened material. 
         [0032]    It is understood that the invention is not limited to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as come within the scope of the following claims.