Envelopes – wrappers – and paperboard boxes – Paperboard box – With closure for an access opening
Reexamination Certificate
2000-12-28
2001-09-04
Elkins, Gary E. (Department: 3727)
Envelopes, wrappers, and paperboard boxes
Paperboard box
With closure for an access opening
C229S114000, C229S150000
Reexamination Certificate
active
06283364
ABSTRACT:
TECHNICAL APPLICABILITY AND FIELD OF THE INVENTION
This invention relates to a disposable container that may be used for packaging foodstuffs. In particular, the invention relates to a clamshell-type container having a positive opening mechanism that may be easily opened by the user.
BACKGROUND OF THE INVENTION
Disposable packaging, in particular, packaging cartons used in the fast food industry, must meet certain technical as well as economic criteria. For economic efficiency, such cartons should be cheap to manufacture in bulk quantities. Technically, the packaging must be constructed of a material that is chemically compatible with the foodstuffs being packaged, and not susceptible to show-through of oil or food juices on the outside of the container. Moreover, the packaging must be sturdy enough to allow handling without damage during a high speed forming process, and to permit stacking of the filled cartons. Such packaging is also desirably of a design that allows nesting of the empty formed containers for efficient storage.
Another desirable feature of such disposable packaging cartons is a closure means that can be easily opened and closed. In this regard, several closure means have been reported in the prior art. U.S. Pat. No. 2,956,720 (Rindal) describes a carton having an arrow lock closure consisting of a combination of a horizontal and angled slits forming a slit closure in one panel of the carton, and an arrow-shaped tab on the edge of a panel overlying the panel containing the slit. Closure is effected by pushing the arrow-shaped tab downward and toward the interior of the carton, thereby pressing the slit closure to separate the horizontally placed slits, thus allowing entry of the arrow tab. Because of the manner in which the slit closure is opened, the lower free end of the tab may be displaced appreciably inwardly against the contents of the carton, thereby forming a product-free, pocket-like area which ensures an opportunity for free entrance of the arrow tab.
U.S. Pat. No. 4,516,718 (Forbes) discloses a clamshell container having a positive locking closure. To close this container, the reference teaches engaging one or more upwardly directed tongue elements positioned at the free edges of a tray portion with one or more slit openings, each of which is positioned closely adjacent to a score line between the top panel and a side wall. By this closure means, the locking tongue is extends above and outside the lid when the carton is closed, and thus may be easily displaced by depressing the locking tongue element when it is desired to open the carton.
U.S. Pat. No. 4,763,832 (Forbes) describes a clamshell container with a bottom lock closure, in which the tray component includes at least one locking slot formed by a continuous cut line located in the tray front wall. This locking slot is closely adjacent to a score line that forms the fold between the bottom panel and front wall, and cooperates with a tongue element on the lid component, such that when the lid component and tray component are brought together to close the carton, the tongue element is automatically guided into the locking slot. The closure means is released by pressing inwardly on the front wall of the lid.
While the prior art, as discussed above, has utilized tab and slot closure elements together in disposable containers such as clamshells, in each instance the tab is exposed and is therefore prone to bending, tearing or other deformation during closure, which can compromise the closure means. Typically, the tab or tongue element is a relatively fragile element of the container because of its relatively small surface area and because it is pendent from and unsupported by the container wall from which it is appended. A closure means having a tab element, which can be opened without direct handling of the tab, is thus desirable.
The prior art therefore evidences a need for a positive locking container having a tab and slot combination closure, in which the tab element is less susceptible to tearing or deformation. Such a container should further be easily opened by applying positive pressure to the exterior of the container without direct handling of the tab. Such a container should also be inexpensive to manufacture, and capable of being stored efficiently before and during use.
SUMMARY OF THE INVENTION
This need in the art is met by the various embodiments of the present invention, which provide a clamshell container having a positive locking closure that is easy to open. This positive locking container may find use in multiple applications including, for example, the foodservice industry.
In particular, the container of the present invention comprises:
a) a tray having a bottom panel and upstanding front, side and rear tray walls, wherein the front tray wall includes a fold line forming an extension of said front tray wall; said tray having a slot cutout located therein; and
b) a lid having a top panel and downwardly extending front, side and rear lid walls, wherein the front lid wall includes a fold line creating an extension of said front lid wall, said extension having a tab element located therein such that when the extension is folded toward the interior of the container, the tab element is inverted to provide an inverted tab locking means;
said container having a tab closure means, which is provided by engagement of the slot cutout with the inverted tab locking means.
The top panel is preferably rectangular in configuration, while the bottom panel is suitably either rectangular or of a curved rectangular configuration to better accommodate a range of food shapes, and also to prevent the user from confusing the lid portion with the tray portion of the container. The front tray wall may be extended to a height greater than the height of the side or rear tray walls. One reason for providing such an extension of the front tray wall is to provide a degree of overlap between the extension and the front lid wall and/or the top panel. In this manner, greater reinforcement is provided to the front lid wall and lid to create a sturdy package.
One element of the positive locking closure of the invention is a tab element formed in an extension portion of the front lid wall. The extension is folded toward the interior of the container when the clamshell is formed, and, accordingly, the tab element is inverted within the interior of the container, The positive locking means further includes a slot cutout, located within the front tray wall, for engagement of the inverted tab element to close the container. This slot cutout may be positioned above, below or contiguous with the fold line of the front tray wall, thereby affording some flexibility in the design of the container depending on the type of material used in its construction and its intended application. The slot cutout preferably comprises a linear top cut formed parallel to the top edge of an extension of the front tray wall, a pair of bottom cuts that are linear and parallel to the top cut, and a curvilinear cut imposed between the pair of bottom cuts to form a lip or open region for accepting a tab element, and a pair of curvilinear side cuts joining the ends of the top cut to the pair of bottom cuts.
The positive locking closure is secured by engaging the inverted tab element with the slot cutout, and the closure means is hidden behind the front walls of the container. In this respect, direct handling of the tab and slot are avoided, and the problems of tearing, bending or other deformation caused by direct handling of the tab are eliminated.
In another aspect, the invention comprises a blank for forming a clamshell container comprising a first portion for forming a lid portion, a second portion for forming a tray portion and a score line or perforation connecting the first portion to the second portion; said first portion comprising a top panel and front, side and rear lid walls, said front lid wall having an extension that includes a tab locking means as a first positive locking closure means; and the second portion comprising a botto
Elkins Gary E.
Westvaco Corporation
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