Envelopes – wrappers – and paperboard boxes – Paperboard box – Including a polygonal – nonrectangular wall
Reexamination Certificate
1999-12-01
2001-05-01
Elkins, Gary E. (Department: 3727)
Envelopes, wrappers, and paperboard boxes
Paperboard box
Including a polygonal, nonrectangular wall
C229S149000, C229S154000, C229S906000
Reexamination Certificate
active
06223979
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to cartons made of paperboard material and, in particular, to paperboard cartons for food products such as pizza, breadsticks, chicken, hamburgers, salads, and the like.
DESCRIPTION OF THE PRIOR ART
Prior art structure can be defined in terms of one-piece versus two-piece construction. A carton of one-piece construction, called a one-piece carton, has a cover member hingedly attached to a tray member at a fold line. A carton of two-piece construction, called a two-piece carton, has separate cover and tray members. A two-piece carton typically has two problems compared to a one-piece carton. First, it's less rigid and has a less-secure cover closure, often resulting in accidental cover opening. Second, it usually requires more material to make, resulting in a more expensive carton.
Prior art structure also can be defined in terms of fixed-corner versus non-fixed-corner construction. A carton of fixed-corner construction, called a fixed-corner carton, has one or more corners formed by a fixed attachment of one wall to another. A fixed attachment between adjacent panels or walls is typically created by glue, staple, or tape. Hence, examples of cartons having one or more corners formed by a fixed attachment of one wall to another include glued-corner paperboard cartons, stapled-corner paperboard cartons, and taped-corner paperboard cartons. A carton that has no fixed attachment of one wall to another by means of glue, staple, or tape would be called a non-fixed-corner carton.
Finally, prior art can be defined in terms of clamshell versus non-clamshell construction. A carton of clamshell construction, called a clamshell carton, is a one-piece carton having a clamshell tray member hingedly attached to a clamshell cover member. As used herein, a “clamshell tray member” is defined as a bottom panel and a plurality of walls disposed obliquely to the bottom panel, with at least two of the walls being joined at a fixed corner. Similarly, as used herein, a “clamshell cover member” is defined as a top panel and a plurality of downward-angling lateral panels disposed obliquely to the top panel, with at least two of the lateral panels being joined at a fixed corner.
By definition, a clamshell carton has at least one fixed corner in the tray member and at least one fixed corner in the cover member. A “fixed corner” is defined as a corner between adjacent panels or walls resulting from a fixed attachment of one panel with the other, that fixed attachment being typically created by glue, staple, or tape. A non-fixed attachment of one wall to another is typically achieved by (a) a flap appending from one wall being enclosed between two parallel panels of an adjacent wall or (b) a flap or tab appending from one wall being enclosed within a slot or hole in an adjacent wall.
In essence, a clamshell carton is a one-piece fixed-corner carton. A two-piece carton with slanting walls is not considered to be a clamshell carton. A salient feature of clamshell cartons is that multiple units can be nested together and, when this is done, cover members nest inside cover members and tray members nest inside tray members. A carton of non-clamshell construction, called a non-clamshell carton, is a carton lacking either the clamshell tray member or the clamshell cover member or both.
Each year millions of restaurant food orders are packaged in clamshell cartons. In the current art of clamshell cartons, the side walls which project upward from the bottom panel do not extend far enough upward to reach the top panel of the cover member. Instead, each side wall extends only far enough to contact the bottom edge of a downward-angling lateral panel of the cover member. Two examples of clamshell cartons in paperboard which illustrate that structure are Fultz et al. U.S. Pat. No. 4,930,681 granted Jun. 5, 1990, and Cai U.S. Pat. No. 5,707,004 granted Jan. 13, 1998.
A main advantage of clamshell cartons is convenience; they require little or no set-up by the user.
However, current paperboard clamshell cartons have a major drawback. Specifically, they are lacking in crush resistance. When vertical downward pressure is applied to one of the lateral panels of the cover member, that vertical downward pressure is transformed into horizontal outward pressure against the top edge of the side wall that underlies the lateral panel. That horizontal outward pressure pushes the top edge of the underlying side wall outward which, in turn, results in a buckling of the entire side section of the carton.
So, there has remained a problem of how to have a paperboard clamshell carton that resists side section buckling. That problem has not been solved by the prior art but is solved by my invention. By solving that problem, a sturdier, more crush-resistant one-piece clamshell carton is provided.
In addition to the above-cited clamshell cartons, the prior art contains non-clamshell cartons having slanting side walls. Examples of such art include Lorenz U.S. Pat. No. 4,960,238 granted Oct. 2, 1990; Whitnell U.S. Pat. No. 5,603,450 granted Feb. 18, 1997; Watanabe U.S. Pat. No. 5,669,552 granted Sept. 23, 1997; and Speese et al. U.S. Pat. No. 5,921,466 granted Jul. 13, 1999.
In conclusion, it would be highly desirable to provide a paperboard clamshell carton that has greater crush resistance and, thereby, overcomes the above-described buckling problem.
OBJECT AND ADVANTAGE
Accordingly, the object of my invention is a paperboard clamshell carton that offers greater crush-resistance, or greater resistance to side section buckling, than current paperboard clamshell cartons offer. That object is accomplished by having the side walls of the tray member extend all the way from the bottom panel to the top panel of the carton, whereby the top edge of the side walls comes into contact with the top panel of the carton. With that structure, when vertical downward pressure is applied to a lateral panel of the cover member, that pressure is transferred to the underlying side wall in the form of vertical downward pressure rather than horizontal outward pressure, thereby reducing the tendency for side section buckling.
The main advantage of my invention is that, during transport, a fewer number of carry-out/delivery food orders will be destroyed by crushing.
Further objects and advantages of the invention will become apparent from consideration of the following detailed description, related drawings, and appended claims.
SUMMARY OF THE INVENTION
My invention is a paperboard clamshell carton wherein (a) the cover member has a distance between opposing lateral panel fold lines that is slightly longer than a distance between top outer edges of opposing side walls in the tray member, (b) the height of the side walls is such that the side walls extend virtually all the way from the bottom panel to the top panel of the carton, (c) a majority portion of lateral panels extending from the cover panel is disposed below the outermost perimeter of the tray member and/or (d) the rear wall is hingedly attached to the bottom panel and the top panel is hingedly attached to the rear wall.
Thereby, in the closed carton format, the lateral panels of the cover member are disposed on an exterior side of the side walls and below an outermost perimeter of the tray member, and the top panel rests on the top outer edge of the side walls, particularly when downward pressure is applied to the cover member.
The structure of my invention distinguishes from that of conventional (prior art) paperboard clamshell cartons in one or more of the following three ways. First, in a conventional paperboard clamshell carton the distance between opposing lateral panel fold lines is less than the distance between the top edges of opposing side walls. Second, in a conventional clamshell carton the side walls do not extend all the way from the bottom panel to the top panel, thereby the top panel does not contact the side walls. Third, in a conventional clamshell carton, a majority portion of the lateral panels is disposed above the outermost perimeter
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