Abstract:
The combination of a container and a screw-type lid is improved by a tamper-evident feature comprising a locking tab on the exterior of the container having upwardly facing teeth and mating teeth on the lid, the teeth on the container and lid being arranged so as be slidable relative to one another while in mutual engagement when the lid is rotated in one direction and to lock to one another when the lid is urged to rotate in an opposite direction. The tab is tearable to terminate the locking action, thereby evidencing tampering. A catch member formed on the container is positioned to engage and cam one of several latch lugs formed on the lid, whereby to establish a locking action with that latch lug. The catch member prevents removal of the lid from the container until the engaged latch lug is pressed inwardly far enough for it to be released from the catch member, whereupon the lid may be unscrewed from the container.

Description:
FIELD OF THE INVENTION 
     The present invention pertains to containers closed off by a lid or cover and means evidencing tampering of the container closure. 
     PRIOR ART 
     Heretofore efforts have been made to provide containers of the type having removable closures with means evidencing efforts to remove the closures. It is especially desirable to have a tamper-evident means for indicating if a container has been opened in the case where it is filled with food, drugs, medicines, or a material that is toxic or irritating to the skin. Tamper-evident means are also desirable to reduce pilfering, e.g., when the containers are filled with small, expensive electronic semiconductor devices. In some cases the tamper-evident means also may serve to render the closures difficult for children to open. Commonly the tamper evident means is either formed integral with the closure or constitutes a separate component that is engaged with both the closure and the container. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     A primary object is to provide a container with novel means for indicating that an effort has been made to remove its cover or lid to gain access to its contents. 
     A further object is to provide a plastic container with a removable closure characterized by a tamper-evident means formed integral with the container and engaged by the closure. 
     Another object is to provide containers with reusable covers or lids that are characterized by novel means for evidencing tampering with the sealed closure. 
     Still another object is to provide a container closure system that includes a tamper-evident means and a child safety lock. 
     The foregoing objects, and other objects stated in or rendered obvious by the following specification are achieved by providing (1) a container and (2) a closure in the form of a cover or lid that fits over and makes a releasable connection with the open top end of the container, with the container being formed with a tamper evident member that is engaged by and makes an interlocking connection with the cover or lid. The tamper evident member is in the form of a tab that is breakable under pressure so that, once broken, it is disengaged from the cover or lid. In the preferred embodiment of the invention the cover or lid has teeth on its underside that interlock with teeth on the breakable tab. The tab functions as a tamper evident feature, since the fact that it has been broken can be easily discerned from inspection and since the torn tab cannot be restored to its original condition. In the preferred embodiment the cover or lid is attached to the container by a screw connection comprising external threads near the top end of the container and internal threads on the lid. When the lid or cover is screwed onto the container it forms a leak-proof seal with the container. In addition, the lid is provided with latch means that contact catch means on the exterior of the container to securely retain the lid on the container. 
     Other features and advantages of the invention are stated in or rendered obvious by the following detailed description of the preferred embodiment of the invention which is to be considered together with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view in elevation showing a container and attached lid embodying the present invention; 
         FIG. 2  is a side elevation of the same container and attached lid rotated 90° from the view of  FIG. 1 ; 
         FIG. 3  is a plan view of the container with the lid removed; 
         FIG. 4  is a bottom view of the lid; 
         FIG. 5  is fragmentary side view in elevation on an enlarged scale of the same container and lid illustrating the interlocking relationship of the locking tab with the teeth on the lid; 
         FIG. 6  is a sectional view in elevation of the upper end of the container taken along line  6 — 6  of  FIG. 5 ; 
         FIG. 7  is a fragmentary cross-sectional view of the container illustrating the upper side of the tab; and 
         FIG. 8  is a fragmentary sectional view in elevation similar to  FIG. 6  but with the lid attached to the container in engaged relation with the locking tab. 
     
    
    
     In the several figures, like numerals designate like components. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-8 , a preferred embodiment of the invention comprises a circular container  2  and a lid or cover  4 . Both the lid and the pail are molded of a plastic material that is relatively stiff yet resilient, e.g., polyethylene, polypropylene or another moldable thermoplastic resin. 
     Container  2  comprises a side wall  8  that preferably is tapered inwardly from top to bottom by several degrees, i.e., the o.d. of the bottom end is smaller than the o.d. of the upper end of the pail, so as to permit a number of containers (without lids) to be stacked one inside the other for storing and shipping purposes. The upper end of side wall  8  has a peripheral outwardly-extending radial flange  10  ( FIGS. 3 ,  6 ,  8 ) that serves to provide resistance to lateral deformation of the upper end of the container and also serves as a seat for lid  4 . 
     Formed on the outer surface  12  of side wall  8  below flange  10  are four pairs of vertically spaced ribs  14 A,  14 B that are inclined relative to the plane of flange  10  so as to serve as helical screw threads. In the following text ribs  14 A,  14 B are referred to as screw thread segments. The four pairs of screw thread segments are uniformly spaced from one another along the circumference of the side wall. Each screw-thread segment extends circumferentially through an angle of about 42°. 
     The upper end of the container also is rigidized by a circumferentially-extending exterior flange  18  located below the screw thread segments and a skirt  20  that is located below flange  18 . Skirt  20  comprises an inclined radially-extending top portion  22  attached to side wall  8  and a depending side portion  24 . The latter may extend parallel to the longitudinal center axis of the container, but preferably it is slanted as shown. A plurality of spaced radially-extending strengthening ribs  26  are formed integral with the exterior surface of side wall  8 , flange  18  and skirt  20 . 
     At two diametrically opposed areas the container has two outwardly-projecting sections  28 A,  28 B that are generally U-shaped in cross-section and have an outwardly projecting lip  30  at their bottom edges. Sections  28 A,  28 B consist of a top wall portion  31  as part of flange  18 , two opposite side wall portions  32  and an outer wall portion  33 . Sections  28 A,  28 B are open at their bottom ends and their outer wall portions  33  are spaced from side wall  8  by an amount sufficient to accommodate a person&#39;s fingers, whereby sections  28 A,  28 B can function as handles for lifting the container with or without lid  4  attached thereto. Preferably handle sections  28 A,  28 B are provided with holes  34  ( FIG. 1 ) to pivotally accommodate the ends of a bail (not shown) whereby the container may function as a pail (bucket). 
     Referring to  FIGS. 1 and 3 , the upper surface of flange  18  is provided with a vertically extending catch element  36  that has one side surface  38  that extends substantially along a radius of the container and an opposite side surface  40  that is slanted inwardly in a clockwise direction, so that its outer edge is further from side surface  38  than its inner edge. The slanted surface  40  leads the radial surface  38  in a counter-clockwise direction along the circumference of the container. 
     Referring now to  FIGS. 2 ,  3  and  5 - 8 , the container is provided with a tamper-evident lock means in the form of a radially-extending tab  42  that is an integral part of flange  18 . Tab  42  projects outwardly of the periphery of flange  18  and is demarcated by a pair of parallel grooves  44 A,  44 B formed in flange  18 . A plurality of upwardly extending teeth  46  are formed on the upper side of tab  42 . As seen in  FIG. 5 , the teeth are of sawtooth shape, having a vertically extending trailing edge and an inclined leading edge. As viewed in  FIG. 3 , the inclined edges lead the vertical edges in a counter-clockwise direction along the circumference of the container. 
     Grooves  44 A,  44 B are defined by a vertical side wall and an inclined bottom wall, with the vertical side walls defining the side edges of tab  42 . Two of the ribs  26  ( 26 A,  26 B), are located in line with grooves  44 A,  44 B, as shown in  FIGS. 2 and 5 , to provide support for flange  18  and thereby facilitate rupture of tab  42  along those grooves. The depth of the grooves is sufficient to allow tab  42  to be severed from flange  18  by a manually applied rupturing force, but not so great as to allow the connection between the tab and rib to be broken accidentally. When rupture occurs along grooves  44 A,  44 B, the inner end of tab  42  will still be attached to side wall  8 , allowing the connection of the tab to wall  8  to function as a hinge whereby the tab can be swung down close to side wall  8 . 
     Referring to  FIGS. 1 ,  2 ,  4  and  8 , lid  4  is formed with a main body section  50  and a rim section  52  that comprises a cylindrical depending inner wall  54  and a circular depending outer wall  56  that is spaced from the inner wall so as to define a channel sized to accommodate flange  10  of the container. The outer wall is slanted so that the width of the channel is greater at its bottom, i.e., at its mouth. 
     Outer wall  56  is formed with four pairs of vertically spaced circumferentially-extending ribs  60 A,  60 B that are inclined so as to serve as screw thread elements, like the ribs  14 A and  14 B. Ribs  60 A,  60 B are spaced apart and have the same pitch as ribs  14 A and  14 B. The four pairs of screw thread segments  60 A,  60 B are uniformly spaced from one another along the circumference of the lid. Each screw thread segment extends circumferentially through an angle of about 42°. Additionally the lower edge of outer wall  56  is provided with four depending latch lugs  64  that are uniformly spaced along the circumference of the lid, plus four sets of teeth  66 . The latter have a sawtooth configuration and are sized and arranged to mesh with teeth  46  of tab  42 . The four sets of teeth  66  occur alternately with catch lugs  64  on lid  4 , and lugs  64  are located relative to screw thread segments  60 A,  60   b  so that one of the lugs  64  will be adjacent to and blocked by catch element  36  (as shown in  FIG. 1 ) when the lid has been screwed onto the container with one set of its teeth  66  engaged with teeth  46  (as shown in FIGS.  2  and  5 ). 
     Preferably, as seen in  FIG. 8 , the body section  50  of the lid is depressed relative to its rim section and is formed with a series of radially-extending ribs  70  on its bottom side that serve to stiffen the body section. As an optional measure, the lid is formed with four vertically-projecting arcuate ribs  72  ( FIG. 1 ) on its upper side that can serve as a grip to facilitate manual unscrewing of the lid and also as stacking guides to facilitate stacking containers one upon the other. 
     The lid is assembled to the pail by engaging its screw threads segments  60 A,  60 B with the screw thread segments  14 A,  14 B of the container and rotating the lid clockwise to lock the lid in place with flange  10  at the top of the container in engagement with the underside of rim section  52  between inner and outer walls  54  and  56 . If a fluid tight seal is required, an elastomeric sealing ring, e.g., an O-ring (not shown), may be installed in the lid in that upper end of the channel between walls  54  and  56  for engagement by flange  10 , with the sealing ring being slightly compressed when the lid is screwed onto the container. Such use of an elastomeric sealing ring is well known, as shown, for example, by U.S. Pat. Nos. 5,725,122 and 5,577,632. 
     The locking of the lid on the container involves two locking mechanisms or actions involving catch element  36  and lips  66  and also teeth  46  and  66 . As the lid is being screwed onto the pail, one of the latch lugs  64  will engage the slanted leading edge  40  of catch element  36  and the latter will provide a camming action that will bend the outer wall  56  of the lid inwardly far enough to allow that lug  64  to slip by the catch element. Due to the resiliency of the material of which the lid is molded, the cammed portion of the outer wall  56  will immediately return to its original shape, bringing the lug  64  back into alignment with the catch element, whereupon the catch element will prevent the lid from being unscrewed from the container unless the outer wall  56  is pressed inwardly enough to allow the blocked latch lug  64  to slip by the catch element. This need to press the outer wall  56  inwardly to free the blocked latch lug  64  constitutes a safety lock. 
     A second locking action is provided by the tamper evident tab  42 . As one of the latch lugs  64  is being cammed inwardly by catch element  36 , one of the sets of teeth  66  will engage and pass along teeth  46  on tab  42 . Engagement of teeth  66  with teeth  46  to achieve the locked state shown in  FIGS. 2 and 5  involve downward deflection of teeth  66  by teeth  46  (and also a lesser upward deflection of teeth  66 ) as a consequence of the inclined edges of sawteeth  66  producing a camming action as they ride up the inclined edges of sawteeth  46 . However, with respect to unlocking the lid, the height (vertical dimension in  FIG. 5 ) of the teeth  46  and  66  is sufficiently large to prevent their disengagement from one another by merely deflecting tab  42  downward away from the lid, since it is difficult to pry the lid upwardly due to the fact that teeth  66  make an exact fit with teeth  46 . Instead the tab  42  must be pushed down with a force sufficient to cause the opposite sides of the tab to break away from flange  18  at grooves  44 A and  44 B, whereupon the tab can be pressed down far enough to separate teeth  46  from teeth  66 . Once that has been accomplished, the lid can be unscrewed, but only if the outer wall  56  is pressed in far enough to allow the captured latch lug  66  to slide past the catch element  36 . However, once the tab has been torn away along grooves  44 A,  44 B, it cannot be restored to its original state as an integral part of flange  18 , thereby making evident that the tampering of the lid/container connection has occurred. It is to be noted that rupturing tab  42  along tear grooves  44 A,  44 B does not affect the locking action provided by catch element  36  and latch lugs  64 . 
     It should be noted that a common industry practice is to apply a plastic screw-type lid to a container by a downward, non-rotating propulsion of the lid towards the container, i.e., by a press-on action. In this case such press-on action is feasible because the lid and container are made of a resilient material, e.g., polyethylene or polypropylene, and also because the outer wall  56  of the lid&#39;s rim is slanted outwardly as shown in FIG.  8 . Although the lid and container each have four screw thread segments, it is contemplated that two, three or more than four segments may be used. 
     Preferably the container has only one catch element  36  as shown, since it has been determined that adequate safety locking is achieved with a single catch element. Nevertheless, for added safety, it is contemplated that the container may have two mutually spaced catch elements positioned so as to cam and block two latch lugs as described when the lid is screwed onto the container. Where two catch means are employed, such as shown in the preferred embodiment of the drawings, it is necessary to free two latch lugs  64  simultaneously from their catch elements  36  in order to permit counter-clockwise unscrewing of the lid. Such simultaneous movement is difficult for to accomplish even for an adult and provides an added measure of safety. 
     The invention lends itself to modifications. Thus, for example, different forms of screw threads may be used. Also, the container need not have handle sections as shown. Also locking tab  42  may be formed with a smaller thickness where it is joined to side wall  8 , thereby permitting it to be torn away from the container. These and still other modifications, including reversal of parts and function, which are obvious to persons skilled in the art may be made without departing from the spirit and scope of the invention as herein disclosed.