Patent Publication Number: US-6905450-B2

Title: Clam shell container with cover and inner tray

Description:
This application is a divisional of Ser. No. 10/057,994, filed Jan. 29, 2002 now U.S. Pat. No. 6,685,022. 

   BACKGROUND OF THE INVENTION 
   Items such as DVD&#39;s, CD&#39;s and VHS cassettes are conventionally packaged in clam shell containers. The clam shell containers are formed by a back cover and a front cover, each hinged to a spine. The remaining three sides of the package are formed by flanges extending from the front and back cover. The inside surface of both the front and back cover form trays for receiving the item. Often, the whole clam shell container is made from a single piece of molded plastic. 
   A more aesthetically pleasing package is formed by a cover made of material such as cardboard, paperboard or chipboard and having plastic trays adhered to the inner surface of the cover. Both the cover and tray are formed with a back and a front hingedly connected to a spine. Problems have arisen with this type of package having two layers adhered together and folded into the clam shell configuration. 
   When a clam shell container formed from two layers of material is assembled, the hinges of the tray are aligned with the hinges of the cover. Difficulty arises in the fact that, when folded, the hinges of the tray having a smaller radius of curvature than the hinges of the cover. The result is that the alignment between the cover and tray is different in the opened and closed positions. Stress placed on the hinges of the tray when the tray is adhered to, and confined by, the cover in the closed geometry and subsequently opened. 
   The prior art has addressed this problem in the past. U.S. Pat. No. 3,355,081 (Kachurchak) discloses a plastic liner on a cardboard box having a notch removed from the liner along fold lines. Also, U.S. Pat. No. 3,654,053 (Toedter) discloses a laminate having material removed from the inner layer along fold lines to facilitate the folding operation. When a tray is thermoformed, however, there is no continuous face-to-face adhesion between the tray and the cover. Also, with these prior art solutions, the laminate has to be fully set before the removal material is performed. 
   It is an object of the invention to provide a clam shell container formed by a cover and tray adhered together accounting for the change in alignment between the two during opening. 
   It is another object of the invention to provide a clam shell container made by a cover and tray adhered together when the tray is a single piece. 
   It is another object of the invention to provide an aesthetically pleasing clam shell container, yet inexpensive to manufacture. 
   It is another object of the invention to provide a clam shell container having a cover and tray reducing stress in the package inherent from the repeated opening and closing of the container. 
   These and other objects of the invention will become apparent after reading the disclosure of the invention. 
   SUMMARY OF THE INVENTION 
   The clam shell container is formed by a cover formed of cardboard, chipboard or other similar material. A thermoform plastic tray is adhered to the inner surface of the cover to form the completed clam shell container. When closed, the edges of the tray move closer to the edges of the cover and the adhesive is allowed to set. When laid open flat, the distance between the edge of the tray and the end cover would increase if not constrained by the bonding. In order to alleviate the stress that occurs when the two are bonded together, the tray is formed with perforations between the left and right tray section and the spine. Once in the open configuration, a small gap is created between the tray sections and the spine. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of the cover; 
       FIG. 2  is a edge view of the cover; 
       FIG. 3  is a plan view of the tray; and 
       FIG. 4  is a view of the completed container after initial opening. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The container  10  is made of a cover  20  and tray  30  adhered to one another. The cover  20  can be seen in FIG.  1 . The cover consists of a front  22  and a back cover  26  hinged to a spine  24 . A first hinge  23  connects the front  22  to the spine  24 . Likewise, a second hinge  25  connects the back  26  to the hinge  24 . An edge view of the cover is seen in FIG.  2 . In the illustrated embodiment, the front  22  and back  26  have a first thickness whereas the spine  24  has a second thickness smaller than that of the front and back. Also, the hinges  23  and  25  have the smallest thickness to aid in the bending movement. In the preferred embodiment, the cover is made up of pasted chipboard having a black craft liner. Alternatively, the cover can be made of corrugated cardboard or paperboard. In such instances, the natural resilience of such material provides a natural hinge, as is known in the art. 
   The tray  30  is illustrated in  FIG. 3  where it can be seen to have a front  32 , a spine  34  and a back  36 . A first hinge  33  connects the front  32  to the spine  34  and a second hinge  35  connects the spine to the back  36 . Each of the hinges  33 ,  35  is provided with perforations, the purpose of which will become clear later. In the preferred embodiment, each perforated line has six perforations measuring 0.025 inches and three perforations measuring 0.040 inches. 
   To assemble the container  10 , the cover  20  is laid flat. The tray is coated with adhesive and centered on the cover. Once centered, the first and second hinge  23 ,  25  of the cover  20  are aligned with the first and second hinge  33 ,  35  of the tray  30 . A space is created between the left, right, top and bottom edge of the tray with the corresponding left, right, top and bottom edge of the cover. After centering, the container  10  is closed and the adhesive allowed to set. 
   When the container is closed, the cover and tray can move relative one another. As the respective hinges of the cover and tray are bent, the hinges of the tray have a smaller radius of curvature than the hinges of the cover. A smaller radius of curvature results in less distance being traveled by the tray than the cover. The net result is for the edges of the tray to move closer to the edges of the cover. Once the adhesive is set with the container closed, the tray is fixed in location relative to the cover. When the ultimate consumer opens the container for the first time, the fixed location of the tray relative to the cover causes stress along the hinges  33 ,  35  of the tray as it opens to a flat configuration. The hinges of the cover  23 ,  25  cover a greater distance in the laid open configuration than the hinges of the tray. This stress causes the breaking of the perforations. When the perforations break, the spine is separated from each of the tray sections by approximately {fraction (1/16)} of an inch. This alleviates any stress in the tray  30 , but allows the manufacturing to take place with a one piece tray, rather than three separate pieces. 
   While the invention has been described with reference to a preferred embodiment, variations and modifications of the invention would be apparent to one of ordinary skill in the art. The invention covers such variations and modifications. For instance, the perforated lines may be replaced with a line of weakness in the hinge formed by a line of reduced thickness or any other type of structure allowing for separation between the spine and the front and back of the tray.