Patent Publication Number: US-2006011632-A1

Title: Tamper indicator lid for container

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention generally relates to plastic-molded lid and containers and, more particularly, to a lid configuration that indicates tampering/pilfering of the contents of a container associated with the lid.  
      2. Background Art  
      Plastic-molded container/lid assemblies represent an advantageous packing solution in some industries. Amongst the advantageous features of plastic-molded container/lid assemblies are the low cost of such assemblies (e.g., relatively low weight of material used), the resilience of the plastic they are made from, the ease of manufacturing such assemblies in various sizes and shapes. Plastic-molded lid/container assemblies are well suited for being used in production lines, due to their resilience, low weight and convenient shapes.  
      Plastic-molded container/lid assemblies are often used in the food industry, for instance in the packing of fresh foodstuff. These assemblies are conveniently usable on filing lines.  
      Plastic parts are vulnerable to tampering/pilfering, as they are often provided without any safety system to prevent such mischief. It would therefore be desired to provide a lid for plastic-molded lid/container assemblies configured to indicate marks of tampering, so as to indicate faulty products.  
     SUMMARY OF INVENTION  
      It is an aim of the present invention to provide a novel lid for a plastic-molded lid/container assembly.  
      It is a further aim of the present invention to provide a lid for a lid/container assembly, having a tamper indicator.  
      Therefore, in accordance with the present invention, there is provided a lid for a container of the type having a peripheral lip at an open end, comprising a cover panel for generally covering the open end of the container; and a peripheral wall on the periphery of the cover panel, the peripheral wall adapted to cooperate with the peripheral lip of the container for releasably securing the lid to the container, the peripheral wall having a tamper indicator tab defined by at least one slit through the peripheral wall, a frangible membrane intersecting the slit, and a protrusion cooperating with the peripheral lip of the container such that the frangible membrane is adapted to break upon removal of the lid from the container; whereby an end of the tamper indicator lid is detached from a remainder of the lid to indicate that the lid has been removed from the container.  
      Further in accordance with the present invention, there is provided a container assembly comprising a container having a peripheral lip at an open end; and a lid having a cover panel for generally covering the open end of the container, and a peripheral wall on the periphery of the cover panel, the peripheral wall adapted to cooperate with the peripheral lip of the container for releasably securing the lid to the container, the peripheral wall having a tamper indicator tab defined by at least one slit through the peripheral wall, a frangible membrane intersecting the slit, and a protrusion cooperating with the peripheral lip of the container such that the frangible membrane is adapted to break upon removal of the lid from the container; whereby an end of the tamper indicator lid is detached from a remainder of the lid to indicate that the lid has been removed from the container.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration a preferred embodiment thereof and in which:  
       FIG. 1  is a perspective view of a lid in accordance with a preferred embodiment of the present invention;  
       FIG. 2  is a sectional view, enlarged, of the lid of  FIG. 1 , as mounted to a container, taken at a breaking tab;  
       FIG. 3  is an elevation view of the lid, illustrating the breaking tab;  
       FIG. 4  is a perspective view of the lid being removed from the container by a lift tab, whereby one of the breaking tabs is broken;  
       FIG. 5  is a perspective view of the lid mounted to the container, illustrating an attempt to remove the lid from the container by one of the breaking tabs; and  
       FIG. 6  is a sectional view, enlarged, of the lid of  FIG. 1 , as mounted to a container, taken at one of the lift tabs. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring concurrently to  FIGS. 1 and 2 , a lid in accordance with a preferred embodiment of the present invention is generally shown at  10 , as mounted to a container A ( FIG. 2 ) having a lip B. The container A is a conventional plastic-molded container adapted for filling line applications.  
      The lid  10  is a recessed lid having a cover panel  12  of circular shape. A skirt  14  surrounds the periphery of the cover panel  12 , so as to cooperate with the lip B of the container A whereby the lid  10  is held captive on the container A, and in sealing engagement therewith. Although the lid  10  is illustrated having a circular shape, it is pointed out that the lid  10  may also be provided in other shapes: rectangular, square, oval and the like. Moreover, a recess-type lid is illustrated in FIGS.  1  to  6  (e.g., for better leak resistance), but it is contemplated to provide the lid of the present invention in a non-recessed configuration.  
      Referring to  FIG. 2 , the skirt  14  of the lid  10  has an inner wall  20  at a junction of the skirt  14  and the cover panel  12 . The skirt  14  also has an outer wall  21 , connected to the inner wall  20  by a shoulder  22 . The skirt  14  forms an annular cavity  23 , in which a rim of the container A, bearing the lip B, will be accommodated when the lid  10  is secured to the container A.  
      More specifically, the outer wall  21  has an undercut  24  (i.e., or protrusion) in the annular cavity  23 . The undercut  24  cooperates with the lip B of the container A, such that the lid  10  is held captive onto the container A. A sealing abutment  29  projects from the shoulder  22  into the annular cavity  23 , and will abut against the lip B when the lid  10  is secured to the container A.  
      As shown in  FIG. 2 , the configuration of the skirt  14  in relation to the geometry of the lip B of the container A provides three surfaces of contact to ensure a generally sealed engagement between the container A and the lid  10 . Firstly, a portion of the inner wall  20  contacts an upper edge of the container A. Secondly, the sealing abutment  29  contacts the lip B of the container A. Thirdly, the undercut  24  contacts the free end of the lip B.  
      As shown concurrently in  FIGS. 1 and 3 , the outer wall  21  has a succession of tamper indicator breaking tabs  26  and lift tabs  28  on the periphery of the lid  10 . In a preferred embodiment of the present invention, the breaking tabs  26  are each defined by a horizontal slit  25  and a pair of vertical frangible membranes  27  (or, alternatively, a single one of the membranes  27 ). On the other hand, the lift tabs  28  are portions of the outer wall  21  between the membranes  27 , and without the horizontal slit  25 . Although the lid  10  illustrated herein is provided with a plurality of breaking tabs  26 , a single breaking tab  26  could be used, although use of such an embodiment would be suggested to indicate that the lid  10  has been fully removed from the container A.  
      The section view of  FIG. 2  is taken at a section of the skirt  14  having a breaking tab  26 . It is seen that the slit  25  extends into the annular cavity  23  of the skirt  14 , such that the undercut  24  is separated into an upper protrusion portion  24 A and a lower protrusion portion  24 B. On the other hand, the section view of  FIG. 6  is taken at a section of the skirt  14  having a lift tab  28 , whereby the undercut  24  is not separated into two parts.  
      The membranes  27  each consist of a channel formed in the outer wall  21 , resulting in a thinner strip of material. The membranes  27  each extend from a bottom edge of the outer wall  21  to an intersection with the slits  25 , thereby defining the breaking tabs  26 .  
      Therefore, the breaking tabs  26  define weaker portions of the outer wall  21 , i.e., more likely to rupture due to the breakable connection between the breaking tabs  26  and the lift tabs  28 . Accordingly, if the lip B of the container A exerts a pressure of the lower portion  24 B of the undercut  24  as illustrated in  FIG. 2 , for instance by an attempt to force the lid  10  off the container A, one of the two membranes  27  of any one of the breaking tabs  26  will fracture, whereby the broken off breaking tab  26  will clearly show as hanging from one end to illustrate that the lid/container assembly has been tampered with. The broken-off breaking tab  26  is the tamper indicator of the lid  10 .  
      Referring to  FIG. 2 , when the lid  10  is installed onto the container A, the lip B bends as a result of the action of the undercut  24  thereon, thereby enabling the lip B to be lodged in the annular cavity  23  of the skirt  14 , without breaking the breaking tabs  26 . The lid  10  is in a suitable position onto the container  10  when the sealing abutment  29  comes into contact with the lip B. It is pointed out that the lid  10  may be installed manually, or on automated equipment (e.g., of a conventional high-speed filling line), onto the container A.  
      In this position, the lip B is lodged in the annular cavity  23  defined by the skirt  14 , and has its free end C held captive by the undercut  24 . More specifically, as illustrated in  FIG. 2 , the free end C of the lip B abuts against the upper portion  24 A of the undercut  24  opposite breaking tabs  26  in the skirt  14 . As illustrated in  FIG. 6 , the free end C of the lip B abuts against the undercut  24  opposite the lift tabs  28 , in addition to the other two contact surfaces between the lip B of the container A and the lid  10 .  
      Referring to  FIG. 2 , when the lid  10  is removed from the container A, the free end C of the lip B catches the lower portion  24 B of the undercut  24 , such that the lid  10  cannot be removed unless additional force is exerted by the handler on the lid  10 . The additional force will result in the break of at least one of the breaking tabs  26 , due to the rupture of one of the vertical membranes  27  of the breaking tabs  26 .  
      As illustrated in  FIG. 4 , in order to remove the lid  10  of the present invention from the container A, any one of the lift tabs  28  is lifted upwardly, whereby the adjacent breaking tab  26  will break as described previously. The lid  10  may thereafter be fully removed from the container A. Once breaking tabs  26  are broken, the lid  10  of the present invention may be reinstalled on the container A in sealable fashion. The above-mentioned surfaces of contact between the lid  10  and the container A ensure the sealing engagement therebetween.  
      As illustrated in  FIG. 5 , if pressure is exerted on one of the breaking tabs  26  in an attempt to remove the lid  10  from the container A, the cooperation between the lower portion  24 B ( FIG. 2 ) of the undercut  24  and the free end C of the lip B will prevent the removal of the lid  10  from the container A.  
      The lid  10  of the present invention may be advantageously molded in a single cycle, with a suitable polymeric material [e.g., polypropylene, polyethylene (LLDPE), polystyrene, and the like], to lower production costs. Alternatively, the lid  10  of the present invention may be subjected to a post-trimming step, wherein the horizontal slits  25  are cut according to the above-described configuration after the molding step. Various types of molding could be used to produce the lid  10  of the present invention, such as injection molding (e.g., thin-wall injection molding), thermoforming. The lid  10  may be printed, for instance, with conventional offset printing equipment. The lid  10  is configured so as to allow lid-to-lid stacking, for instance, using spin-bar or screw-type stacking equipment.  
      It is within the ambit of the present invention to cover any obvious modifications of the embodiments described herein, provided such modifications fall within the scope of the appended claims.