Patent Publication Number: US-6988653-B2

Title: Foldable carton

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation-in-part of U.S. patent application Ser. No. 09/762,095, now abandoned, filed on Feb. 2, 2001 which is a 371 of PCT/AU99/00632 filed Aug. 4, 1999, which claims priority from Australian Provisional Application No. PP 5037 filed on Aug. 4, 1998. 

   BACKGROUND OF THE INVENTION 
   1. The Field of the Invention 
   This invention relates to collapsible packaging such as cartons and the like which are generally formed from blanks formed from a substantially rigid sheet material whereby the blanks are folded to form a carton. 
   2. The Relevant Technology 
   The cartons to which the invention relates are used in a wide variety of circumstances and one particular example of the application of the cartons relates to the forms of packaging used with take-away food items. It is a common characteristic of such cartons that they are not capable of accommodating liquid contents without the utilisation of a supplementary containment means. As a result, in the event of any spillage within the carton the liquid contents of the carton will leak and can create an undesirable circumstance for customers. 
   In the past, attempts have been made to provide cartons which can to some degree overcome this problem. One example of such a carton is disclosed in U.S. Pat. No. 4,471,904 which provides a carton whereby the floor is held in a raised position from the lower limit of the carton. However, in order for the carton to be foldable there is no closed junction between the floor panel and the end and side panels. As a result, there is still the likelihood of leakage therebetween. A further example comprises that which is disclosed in U.S. Pat. No. 2,430,755. However, the carton disclosed in that specification is not one that which is capable of being folded and providing a closed junction between the floor and the side panels. 
   It is desirable to provide a carton which when assembled from a blank can be folded to lie in a substantially flat condition and which can be readily unfolded into an erect condition whereby when in the erect condition no further action or containment means need be provided in order to prevent the leakage of the contents of the carton escaping from the base of the carton. 
   SUMMARY OF THE INVENTION 
   Accordingly the invention resides in a collapsible carton which is formed from a blank which when formed from the blank is capable of being folded between a folded flat condition and an erect condition whereby when in the erect condition the carton has a floor, two opposed end panels and two opposed side panels to define a liquid tight generally rectangular closed prismatic shaped space, the end panels and the side panels having substantially the same height wherein the floor panel is formed of a single panel and the junction between the floor and each of the end panels and each of the side panel is defined by a closed fold line therebetween, the end panels each having a pair of first diagonal fold lines extending from the junction between the sides of the floor and the sides of the respective end panel and converging to terminate at a transverse central axis of the end panel, said first diagonal fold lines being substantially perpendicular to each other, said end panels have a height being equal to or greater than the termination of the diagonals, wherein the floor is provided with a first central fold line which is substantially centrally located and which extends between the end panels and is adapted to permit the floor to fold inwardly into the space about the first central fold line while the first diagonal fold lines fold, said end panels being provided with a second central fold line extending centrally from the floor to an opposed edge of the end panel, each end panel and each side panel formed with an extension panel, said extension panels being of substantially the same height and being hingedly supported from their respective end or side panel, wherein in the erected carton the abutting edges of adjacent extension panels are defined by a closed fold line, the extension panel of each end panel being formed with a pair of second diagonal fold lines extending between the junction between the end panel and the extension panel at the sides thereof and converging to terminate at the junction of the second fold line with the outer edge of the extension panel, whereby on the erection of the carton the extension panels of each end panel fold about the second diagonal fold lines and the junction with the end panels to an intermediate position where the extension panels of the side panels fold over the space to close the space and lie parallel to said floor panel, the extension panels of the end panels being further foldable about their junction with their respective end panels to lie in a self locked position parallel to and adjacent their respective end panels on an outside of said space at which self locked position a biasing force is applied to the extension panels of the end panels in a direction of their respective end panels. 
   Preferably when in the erect condition said floor panel and said junction between floor panel and each of said end panels and side panels lie on a common plane. 
   According to a preferred feature of the invention the termination of the diagonals defines the height of the side panel. 
   According to a preferred feature of tile invention the carton is formed from a blank where the end and side panels are each hingedly supported from the edge of the floor through a fold line. 
   According to a preferred feature of the above feature in the blank the adjacent sides of adjacent end and side panels are interconnected by a web having an edge which is substantially at 45° to the adjacent edges of the adjacent end and side panels and which has a further diagonal fold line extending from the junction of the adjacent end and side panels which bisects the angle therebetween. 
   According to a preferred feature of the invention in the blank the side panels are hingedly supported from the floor and the end panels are hingedly supported from the side panels. 
   According to a further preferred feature of the previous feature in the blank one end panel is supported from one of the side panels and the other end panel is supported from the other side panel. 
   According to an alternative preferred feature of the previous feature in the blank each side panel supports a portion of an end panel whereby the portions of the end panels co-operate to define the end panels when the blank is folded to an erect condition, 
   According to each preferred feature of the invention wherein in the blank at least one of a pair of edges of the end and side panels which are to become interengaged when the carton is formed are provided with glue flaps. 
   The invention will be more fully understood in the light of the following description of several specific embodiments. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The description is made with reference to the accompanying drawings of which; 
       FIG. 1  is a plan view of a blank according to the first embodiment; 
       FIG. 2  is an isometric view of a partially folded blank according to the first embodiment; 
       FIG. 3  is an isometric view of an erected carton formed from the blank of the first embodiment with the extension panels open; 
       FIG. 4  is an isometric view of an erected carton formed from the blank of the first embodiment with the extension panels partially closed; 
       FIG. 5  is an isometric view of an erected carton formed from the blank of the first embodiment with the extension panels fully closed; 
       FIG. 6  is an isometric view of a folded carton formed of a blank according to the first embodiment; 
       FIG. 7  is a plan view of a blank according to the second embodiment; 
       FIG. 8  is an isometric view of an erected carton formed from a blank of the second embodiment with the extension panels open; 
       FIG. 9  is an isometric view of an erected carton formed from the blank of the second embodiment with the extension panels partially closed; 
       FIG. 10  is an isometric view of an erected carton formed from the blank of the second embodiment with the extension panels fully closed; 
       FIG. 11  is an isometric view of a folded carton formed from a blank of the second embodiment; 
       FIG. 12  is a plan view of a blank according to the third embodiment; 
       FIG. 13  is an isometric view of an erected carton formed using the blank of the third embodiment with the extension panels open; 
       FIG. 14  is an isometric view of an erected carton formed from the blank of the third embodiment with the extension panels partially closed; 
       FIG. 15  is an isometric view of an erected carton formed from the blank of the third embodiment with the extension panels fully closed; 
       FIG. 16  is an isometric view of a folded carton formed from the blank of the third embodiment; 
       FIG. 17  is a plan view of a blank according to the fourth embodiment; 
       FIG. 18  is an isometric view of an erected carton formed from a blank according to the fourth embodiment with the extension panels open; 
       FIG. 19  is an isometric view of an erected carton formed from the blank of the fourth embodiment with the extension panels partially closed; 
       FIG. 20  is an isometric view of an erected carton formed from the blank of the fourth embodiment with the extension panels fully closed; 
       FIG. 21  is an isometric view of a folded carton formed from a blank according to the fourth embodiment; 
       FIG. 22  is a plan view of a blank according to the fifth embodiment; 
       FIG. 23  is an isometric view of an erected carton formed from a blank according to the fifth embodiment with the extension panels open; 
       FIG. 24  is an isometric view of an erected carton formed from the blank of the fifth embodiment with the extension panels partially closed; 
       FIG. 25  is an isometric view of an erected carton formed form the blank of the fifth embodiment with the extension panels fully closed; 
       FIG. 26  is an isometric view of a folded carton formed from a blank according to the fifth embodiment; 
       FIG. 27  is a plan view of a blank according to the sixth embodiment; and 
       FIGS. 28   a  to  28   g  illustrate the assembly of a carton according to the sixth embodiment from the blank shown at  FIG. 27 . 
   

   BEST MODES FOR CARRYING OUT THE INVENTION 
   Each of the embodiments are directed to cartons which are formed from a stiff sheet material such as cardboard where the sheet material is formed into a blank and which can be folded to form a carton whereby when the carton has been formed it can be readily folded into a substantially flat condition and can be subsequently erected from the folded flat condition to provide a carton defining a liquid tight generally rectangular prismatic shaped space whereby the junctions between the floor panel and the side panels and end panels and the junctions between the end panels and the side panels are closed and are resistant to the leakage of the contents. In forming the carton from the blank the formed carton may initially take the form of the folded carton which can then be erected into the carton when it is required. Alternatively in forming the carton from the blank it may initially take the form of the erected carton to be then capable of being folded into a substantially flat condition for transportation and/or storage and subsequent unfolding into an erected carton when required. 
   A significant feature of each of the embodiments relates to the closure of the cartons. This is achieved through extension panels to each of the side panels and end panels where the extension panels have substantially the same height and adjacent extension panels are interconnected at the adjacent edges. The extension panels on each of the end panels are capable of folding about the junction with the respective end panel and about diagonal fold lines in the extension panel. This will result in the folded extension panel extending laterally from the respective end panel and as a further result the extension panels on the side panels will have been caused to have hinged about their junction with the respective side panel to overlie the space defined by the carton. It has been found that because of the construction of the carton where end panels, the side panels and the floor panel are all closed or fully joined (i.e. formed without any discontinuities such as holes, slots or openings) that, on hinging the folded extension panel about its junction with the respective end panel to a position (locked position) parallel and alongside the end panel, a biasing force is applied to the folded extension panel causing it to move towards the end panel and thus be retained at that locked position. Without wishing to be bound by theory, this bias force is believed to arise from tension within the panels created due to the junctions of the panels being closed or filly joined. 
   The first embodiment as shown at  FIGS. 1 ,  2 ,  3 ,  4 ,  5  and  6  comprises a carton which is formed of a blank shown at  FIG. 1  where the carton has a floor panel  11 , two end panels  12  and  13  and two side panels  14  and  15 . Each of the end panels  12  and  13  and each of the side panels  14  and  15  are provided with an outer extension panel  16 ,  17 ,  18  and  19  respectively which when the carton is erected combine to provide the closure for the carton. Each of the end panels  12  and  13  and the side panels  14  and  15  are formed integrally with the floor panel  11  and are connected to the floor panel  11  by a fold line whereby they can be folded to be substantially perpendicular to the floor panel  11  which will bring their adjacent side edges into abutment with each other. 
   The side edges of the side panels  14  and  15  and their extension panels  18  and  19  are provided with glue flaps  20  which are adapted to be able to overlie the edge portions of the inner faces of the adjacent end panels  12  and  13  and their respective extension panels  16  and  17  when the side panels and end panels are folded along their fold line with the floor panel  11  as described above. The glue flaps  20  may be rendered self adherent such that they will adhere to the edge portions of end panels  12  or  13  or may have an adhesive applied thereto prior to folding to effect such adhesion. As a result of the fixing of the glue flaps  20  to the end panels  12  and  13  and their respective extension panels  16  and  17  the junctions between the end panels  12  and  13  and the side panels  14  and  15  and between the respective extension panels are sealingly closed. 
   Each of the end panels  12  and  13  are provided with a pair of first diagonal fold lines  21  and  22  which extend from the junction between the adjacent edges of the end panel and the adjacent side panel and terminate at the central axis of the end panel whereby the diagonal fold lines  21  and  22  are perpendicular to each other. 
   In addition in the case of the first embodiment the floor panel  11  is provided with a first central fold line  23  which is centrally located and extends between the end panels  12  and  13 . Each of the end panels  12  and  13  and the respective extension panels  16  and  17  are formed with a second central fold line  24  which is co-linear in the folded blank shown in  FIG. 1  with the first central fold line of the floor panel  11 . 
   In addition each of the extension panels  16  and  17  on the end panels  12  and  13  are provided with a pair of second diagonal fold lines  25  and  26  which are parallel to the first diagonal fold lines  21  and  22 . The second diagonal fold lines  25  and  26  extend from the junction between the respective end panel and the extension panel to converge and terminate at the outer edge of the extension panel. 
   In the formation of the carton from the blank, the side panels  14  and  15  and the end panels  12  and  13  are folded to be substantially perpendicular to the floor panel  11  which brings the glue flaps  20  into face to face engagement with the adjacent edge portions of the inner faces of respective end panels  12  and  13  and their extension panels  16  and  17 .  FIG. 2  illustrates the carton partially erected where one end panel  12  and its extension panel  16  has been folded with the adjacent side panel  14  and its extension panel  18  to be perpendicular to the floor panel  11 . The glue flaps  20  on the side panels  14  and  15  and their extension panels  18  and  19  are then bonded to the respective end panels  12  and  13  and their extension panels  16  and  17  to define a substantially cubic carton as shown at  FIG. 3  where the extension panels  16 ,  17 ,  18  and  19  are open. Once erected the side panels, end panels and floor panel of the formed carton define a liquid tight space whereby the folded junctions between the floor panel and each of the side panels and end panel is substantially continuous and is closed and the junctions between the side panels and the end panels are also continuous and sealed. 
   Furthermore, the carton can be readily folded to a substantially flat condition as shown at  FIG. 6 . This is effected by causing the first central fold line  23  of the floor panel  11  to fold such that the first central fold line  23  moves inwardly. In addition the first diagonal fold lines  21  and  22  of each of the end panels to move inwardly to lie between the side panels  14  and  15  to overlie the portions of the floor panel  11  to each side of the first central fold line  23  and the portion of the second central fold line  24  between the junction of the first diagonal fold lines  21  and the junction between the respective end panel  12  and  13  and the floor panel  11  moves to overlie the first central fold line  23 . In addition the portion of the second central fold line  24  between the junction of the first diagonal fold line  21  and the outer edge of the extension panel  16  and  17  folds such that it moves inwardly to lie between the side panels  14  and  15 . This action brings the side panels together with the folded floor panel  11  and folded end panels  16  and  17  located there between as shown at  FIG. 6 . 
   When the carton is in the erected condition as shown at  FIG. 3  the carton can be closed by causing the second diagonal fold lines to fold such that the inner faces of the extensions  17  and  16  end panels to each side of the second diagonal fold lines  25  and  26  fold inwardly about the second diagonal fold lines towards each other as shown at  FIG. 4 . As a result the extensions  17  and  16  of the end panels fold outward from each end of the carton which serves to bring the extensions  18  and  19  on the side panels  14  and  15  towards each other to overlie the space created by the carton between the floor panel, the side panels and the end panels. The folded extensions of the end panels can ten be folded downwardly about the fold line defined between the junction of each end panel  12  and  13  and its respective extension  16  and  17  whereby the folded extension lies closely adjacent and substantially parallel to the outer face of the respective end panel as shown at  FIG. 5 . Also the floor panel  11  and the junctions of the floor panel  11  and the end and side panels panels  12 ,  13 ,  14  and  15  lie on a common plane. 
   It has been found that because of the construction of the carton where end panels, the side panels and the floor panel are all fixed together and are closed (i.e. formed without any holes, slots or openings) that on attempting to hinge the folded extension panels  16  and  17  about their junctions with the respective end panels  12  and  13  from the lateral position as shown at  FIG. 4  to a locked position parallel and alongside the end panels as shown at  FIG. 5 , an initial biasing force is generated by the carton and applied to the folded extension panel as it moves to the locked position resisting its movement to the locked position. However, at an intermediate stage of that movement the initial force is replaced by a contrary biasing force generated by the carton which causes the folded extension panel to move towards the end panel and thus be retained at the locked position. To move the folded extensions from the locked position requires the external application of sufficient force to counteract the contrary biasing force. Thus the carton  10  can be closed and retained in the closed condition without the application of any other means or action. Indeed this provides a “snap” lock facility where the carton snap closes and is self held in a closed condition after folding the extension panels  16  and  17  through an intermediate angle below their lateral (horizontal) positions. 
   In the case of the second embodiment as shown at  FIGS. 7 to 11  the carton is of a generally similar form to that of the first embodiment with the exception that in the case of the side panels  214  and  215  the edges are not provided with glue flaps but rather the edges of the end panels  212  and  213  are interconnected with the adjacent edges of the adjacent side panels  214  and  215  by a web element  227  which has an outer edge which is disposed at substantially 45° to the edges of the respective end panel and side panel. In addition the webs  227  are each provided with a third diagonal fold line  228  which extends from the junction between the adjacent edges of the adjacent end panel and side panel where the third diagonal fold line  228  bisects the angle between the adjacent end panel and side panel. 
   In addition the side edges of the extensions  216  and  217  of the end panels  212  and  213  are provided with glue flaps  220  which are adapted to be able to overlie the edge portions of the inner faces of the adjacent extension panels  218  and  219  of the side panels  214  and  215  when the side panels and end panels are folded along their fold line with the floor panel  211 . The glue flaps  220  may be rendered self adherent such that they will adhere to the edge portions of extension panels  218  and  219  of the side panels  214  and  215  or may have an adhesive applied thereto prior to folding to effect such adhesion. As a result of the fixing of the glue flaps  220  to the extension panels  218  and  219  the junctions between the extension panels on the side panels  214  and  215  and the end panels  212  and  213  are sealingly closed. 
   In folding the blank to form the erected carton as shown in  FIG. 8  each web  227  is folded about the junction between the respective end panel and side panel and the third diagonal fold line  228  is caused to fold and move inwardly such that the web is folded and lies within the carton adjacent the respective side wall, to be bonded thereto. 
   The erected carton can then be folded into flat condition as shown at  FIG. 11  in the same manner as has been described in relation to the first embodiment. In addition the erected carton can be closed in the same manner as has been described in relation to the first embodiment and as shown at  FIGS. 9 and 10  with the same locking action as described in relation to the first embodiment. 
   The third embodiment as shown at  FIGS. 12 to 16  is of generally similar form to the first and second embodiment in terms of the configuration of the erected carton as shown at  FIG. 13 . The difference in relation to the third embodiment relates to the configuration of the blank as shown at  FIG. 13  in that the end panels  412  and  413  are interconnected with one or the other side panel  418  or  419  respectively. When the carton has been formed from the blank as shown at  FIG. 13  it can be folded and collapsed in a similar manner to that of the first and second embodiment as shown at  FIG. 16  and can be closed in a similar manner to that of the first and second embodiment as shown at  FIGS. 14 and 15  with the same locking action as described in relation to the first embodiment. 
   The fourth embodiment of  FIGS. 17 to 21  comprises a carton which is of generally similar form to the first and second embodiment in terms of the configuration of the erected carton as shown at  FIG. 18 . The carton is formed from a blank where each of the side panels  614  and  615  and their extensions supports a portion of each end panel and their extensions which when the carton is erected combine to form the end panels. When the carton has been formed from the blank as shown at  FIG. 18  it can be folded and collapsed in a similar manner to that of the first, second and third embodiment as shown at  FIG. 21  and can be closed in a similar manner to that of the first and second embodiment as shown at  FIGS. 19 and 20  with the same locking action as described in relation to the first embodiment. 
   The fifth embodiment of  FIGS. 22 to 26  is of a similar form to that of the third embodiment of  FIGS. 17 to 21  with the exception that the adjacent edges of the portions of the end panels  712   a ,  712   b ,  713   a  and  713   b  and the floor panel  711  are interconnected by web members  727  having an edge which is at 45 degrees to the respective edges of the portion of the respective end panel and the floor panel. Each web  727  is provided with a third diagonal fold line  728  extending from the junction between the respective portion of the end panel and the floor panel and which bisects the angle therebetween. In formation of the carton the web panels  727  are folded inwardly as a result of the third diagonal fold line folding inwardly into the interior of the carton whereby on the carton being erected the folded web  727  lies against the end panel and is glued thereto. When the carton has been formed from the blank as shown at  FIG. 23  it can be folded and collapsed in a similar manner to that of the first, second, third and fourth embodiment as shown at  FIG. 26  and can be closed in a similar manner to that of the first and second embodiment as shown at  FIGS. 24 and 25  with the same locking action as described in relation to the first embodiment. 
   The sixth embodiment of  FIGS. 27 and 28   a  to  28   g  is of very similar form to the first embodiment as shown at  FIGS. 1 to 6  and the same reference numerals have been used in respect of corresponding features. The only difference is that the sixth embodiment includes a transverse fold line  30  formed in each of the end panels  12  and  13  and which extends from the point of intersection of the first diagonal fold lines  21  and  22  to one side of each end panel  12  and  13 . The transverse fold line facilitates the folding of the blank to form a carton. The steps involved in forming the carton are illustrated at  FIGS. 28   a  to  28   g.    
   The first step involves folding the glue flaps  20  provided on the side panel  15  and extension panel  19  which are remote from the transverse fold line  30  inwardly such that they overlie the respective panel  15  and  19  respectively as shown at  FIG. 28   a . The second step involves folding each end panel  12  and  13  about the first diagonal folds lines  21  and  22  and simultaneously folding the end panel  12  and  13  about the transverse fold line  30  to cause the outer portion of each end panel to underlie the portion of the end panel defined by the first diagonals  21  and  22  as shown at  FIG. 28   b . The third step involves folding the glue flaps  20  provided on the side panel  14  and extension panel  18  which are proximate the transverse fold line  30 , inwardly such that they overlie the respective panel  14  and  18  respectively as shown at  FIG. 28   c . The fourth step involves folding each end panel  12  and  13  about the junction with the floor panel  11  such that the end panels  12  and  13  in their entirety overlie the floor panel  11  as shown at  FIG. 28   d . The fifth step involves folding the side panel  15  which is remote from the transverse fold line  30  about the junction with the floor panel  11  after the exposed faces of the glue flaps  20  of that side panel and its extension panel  19  have been rendered such that they will adhere to the opposed faces of the end panels  12  and  13  as shown at  FIG. 28   e . The sixth step involves folding the blank as folded to that point in time about the central fold line  23  in the floor panel  11  as shown at  FIG. 28   f . The final step involves folding the side panel  14  which is proximate the transverse fold line  30  about the junction with the floor panel  11  after the exposed faces of the glue flaps  20  of that side panel and its extension panel  18  have been rendered such that they will adhere to the opposed faces of the end panels  12  and  13  as shown at  FIG. 28   g . The resultant folded blank will take the form as shown at  FIG. 6  in relation to the first embodiment and can be opened to form an erected carton as shown at  FIG. 3  in relation to the first embodiment and can be folded in the same manner as is described in regard to the first embodiment and as shown at  FIGS. 4 and 5  with the same locking action as described in relation to the first embodiment. 
   The above folding sequence in relation to the sixth embodiment is given by way of example only. The folding sequence can vary depending upon the nature of the folding facilities that are available. 
   Throughout the specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. 
   It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiments described above.