Abstract:
A drink-thru lid for a drinking cup including an annular mounting portion for sealingly engaging the drinking cup, wherein the annular mounting portion includes a downwardly extending annular skirt. The lid further includes a tear-back section extending from the annular skirt to a hinge portion located in a medial portion of the lid. The tear-back section includes a raised protrusion extending outwardly from an upper surface of the lid. A recess is further formed in a medial portion of the lid on the opposite side of the hinge portion from the raised protrusion, wherein the tear-back section may be torn away from the lid on its sides and pivoted about the hinge portion until the raised protrusion is received within the recess for holding said pivotal flap open. The raised protrusion and the recess are shaped such that the raised protrusion is frictionally engaged by the end walls of the recess. The recess further includes a straw slot formed therein, wherein the straw slot is defined by two sloping side walls extending from an upper surface of the lid and converging together at a frangible juncture formed in the deepest portion of the recess.

Description:
This application is a Divisional application of Ser. No. 08/703,771, filed Aug. 27, 1996, now U.S. Pat. No. 5,947,323. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     The present invention relates generally to lids for beverage containers and more specifically to lids having a tear-back drink-thru opening flap which is securably held in an open position within a straw depression formed in the lids. 
     BACKGROUND OF THE INVENTION 
     It is well-known to provide covers for drinking containers to prevent the spillage of the contents of the container. Many prior art covers incorporate an opening in the top of the cover in order to allow drinking of the contents either in the normal drinking fashion or by the insertion of a straw. Some covers have an opening which is sealed by a depressible tab such that when the tab is depressed by the insertion of a straw, the opening is unsealed for drinking the contents of the container. U.S. Pat. No. 3,048,317 issued to Cochrane et al. discloses one such lid having an opening for a straw disposed in a depression formed in the lid with an integrally formed hinged flap in the bottom of the depression. The hinged flap is severed from the lid about the majority of the periphery of the flap to pivot open when a pressure is exerted on the flap by the end of a straw. However, unless the hinged opening is exactly the same diameter as the straw, the fluid within the cup may spill out the opening between the straw and the sides of the opening once the hinged flap has been pivoted open. 
     Other covers utilize a releasable drinking flap in order to prevent the sloshing of the contents out of the containers. An example of this type of cover is disclosed in U.S. Pat. No. 4,738,373 issued to DeParales, which shows a cover having a hinged tab which is defined by score lines formed in the cover leading from the rim of the cover to a hinge positioned in the medial portion of the cover. A recess is formed in the cover on the opposite of the hinge from the tab, wherein the recess receives the rim portion of the tab once the tab is torn open and pivoted about the hinge in order to retain the hinged tab in an open position. However, if the user desired to use a straw with a cover of this type, the straw would have to be inserted into the opening created by the tearing open of the hinged tab. This would create an exceptionally large opening for a straw, allowing the straw to float about and allowing the contents of the cup to be spilled. 
     In an effort to overcome the aforementioned shortcomings, other covers have been proposed utilizing both a straw slot and a releasable flap, depending upon the desired use by the consumer. An example of this type of cover is disclosed in U.S. Pat. No. 4,090,660 to Schram et al., which discloses a cup lid having a liftable tab which snap fits on the rim of a cup with a straw slot formed in the portion of the lid constituting the liftable tab. This design, however, does not include a feature incorporated into the lid which will retain the liftable tab in an open position for convenient repeated drinking from the opening created by the liftable tab. 
     Another example of a prior art drinking lid utilizing both a straw slot and a releasable flap is disclosed in U.S. Pat. No. 5,335,812 issued to Boller, which shows a lid having a straw puncturable area formed in a rupturable depression in the lid. The lid further includes a flap defined by lines of weakness that may be torn and pivoted to overlie a central portion of the lid to retain the flap in an open position. Of course, designs of this general type forming a retaining portion in the center of the lid to hold the flap open as well as forming a separate rupturable depression for a straw are difficult to mold due to the number of depressions and features which must be formed in the cup lid. 
     Yet another type of prior art drinking lid utilizing both a straw slot and a releasable flap is disclosed in U.S. Pat. No. 3,994,411 issued to Elfelt et al., which shows a lid having a foldback drink opening. A pull tab formed on the edge of the rim of the foldback portion is insertable in a straw slit formed in the lid in order to hold the foldback portion in an open position. This foldback drink opening requires a great amount of attention by the user to insert the pull tab into the narrow straw slot in order to hold the foldback portion of the lid open. Furthermore, since the straw slot must be forced open to receive the pull tab, the straw slot will be slightly ajar when retaining the pull tab which can allow the contents of the cup to spill therethrough. 
     Clearly, there is a need for a drink-thru cup lid which provides both a straw slot and a tear-back flap which is simple to form and which does not require multiple separate components to be formed in the lid for each drink-thru feature. Moreover, there is a need for a drink-thru cup lid which securably retains the tear-back flap in place within the straw slot depression without rupturing the cup lid in the straw slot area. 
     SUMMARY OF THE INVENTION 
     A primary object of the present invention is to provide a drink-thru cup lid design which overcomes the aforementioned shortcomings associated with prior art designs. 
     A further object of the present invention is to provide a drink-thru cup lid having a straw slot and a tear-back flap which is simple to manufacture and which does not require multiple separate components to be formed in the lid for each drink-thru feature. 
     Yet another object of the present invention is to provide a drink-thru cup lid wherein the tear-back flap is securably retained in place within the straw slot depression. 
     A still further object of the present invention is to provide a drink-thru cup lid wherein the tear-back flap is securably retained in place within the straw slot depression without rupturing the cup lid in the straw slot area. 
     Yet another object of the present invention is to provide a drink-thru cup lid wherein the skirt of the cup lid includes a plurality of interrupted beads formed therein for securing the cup lid to the brim of a cup. 
     It is yet another object of the present invention is to provide a drink-thru cup lid, wherein the walls of the straw slot bend without fracturing to conform to the shape of the straw as the straw is inserted into the straw slot in order to seal the cup lid around the straw to prevent the contents of the cup from spilling out of the straw slot. 
     These, as well as additional objects of the present invention, are achieved by providing a drink-thru lid for a drinking cup including an annular mounting portion for sealingly engaging the drinking cup, wherein the annular mounting portion includes a downwardly extending annular skirt. The lid further includes a pivotal flap extending from the annular skirt to a hinge portion located in a medial portion of the lid. A raised protrusion extends outwardly from an upper surface of the lid where the protrusion is positioned on the pivotal flap between the hinge portion and the annular mounting portion. A recess is further formed in a medial portion of the lid on the opposite side of the hinge portion from the raised protrusion, wherein the pivotal flap may be torn away from the lid on its sides and pivoted about the hinge portion until the raised protrusion is received within the recess for holding said pivotal flap open. The raised protrusion and the recess are shaped such that the raised protrusion is matingly received within the recess with end surfaces of the raised protrusion frictionally engaging end walls of the recess. The recess further includes a straw slot formed therein, wherein the straw slot is defined by two sloping side walls extending from an upper surface of the lid and converging together at a frangible line of weakness formed in the deepest portion of the recess. The sloping side walls also bend to conform to the shape of the straw as a straw is inserted into the straw slot in order to seal the lid around the straw. 
     In one embodiment of the cup lid of the present invention, a plurality of interrupted beads are formed about the annular skirt to secure the lid to a brim of a cup. The beads are spaced apart from oneanother with beads of a first length being formed in the skirt outside of the section in the skirt included in the pivotal flap and two beads of a second shorter length than the first length being formed in the section of the skirt included in the pivotal flap. The configuration allows the pivotal flap to securably be reattached to the brim of the cup after the pivotal flap has already been torn open. 
     These, as well as additional objects of the present invention will become apparent from the following detailed description when read in light of the several figures. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a lid in accordance with the present invention. 
     FIG. 2 is a perspective view of the lid illustrated in FIG. 1 with an opening formed by tearing back a portion of the lid. 
     FIG. 3 is a top plan view of the lid illustrated in FIG.  1 . 
     FIG. 4 is a cross-sectional side view of the lid of FIG. 1 taken along line IV—IV of FIG.  3 . 
     FIG. 5 is a cross-sectional side view of the lid of FIG. 4 in a stacked relationship with another lid. 
     FIG. 6 is a cross-sectional side view of the mold used to form beads in the skirt of the lid of FIG.  1 . 
     FIG. 7 is an enlarged, cross-sectional side view of the area A of the mold of FIG.  6 . 
     FIG. 8 is a cross-sectional side view of the mold used to form the lid of FIG.  1 . 
     FIGS. 9-11 illustrate a process of inserting a straw through the lid in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention is generally embodied in a lid  10  for a drinking cup  12 . The lid  10  may be used with cups of various types, and is particularly suitable for use with disposable cups of the type commonly used as carry-out containers for beverages such as coffee and the like. Such cups are commonly made of Styrofoam or paper. The drinking cup  12  has a generally circular upper lip or rim  14  with a bead formed on it for receiving and securing the lid  10  thereon. 
     Referring now to FIGS. 1,  2 , and  3 , the lid  10  of the present invention is illustrated. The lid  10  provides a cover for the cup  12  which inhibits spillage and reduces heat transfer between the beverage and the surrounding atmosphere. The lid  10  is secured in place on the cup  12  by an annular mounting portion  16  which engages the rim or lip  14  of the cup  12 , wherein the annular mounting portion  16  includes a downwardly extending skirt  17  which forms the outer peripheral circumference of the lid  10 . A portion  18  of the lid  10  may be torn back to provide an opening  20  in the lid  10  to enable drinking from the cup  12  without removal of the lid  10 . The lid also includes a straw slot opening  22  which functions as a means for facilitating the insertion of a drinking straw (not shown) into the cup  12  for withdrawing liquid by suction. 
     A central raised portion  24  is formed about a substantial portion of a medial area within the circumference of the lid  10  with an upstanding annular wall  26  forming the side surfaces of the central raised portion  24 . Bridging the space between the mounting portion  16  and the upstanding annular wall  26  is an annular channel  28  which readily receives any fluid which may flow out of the opening  20  when the container is jarred or which may spill during consumption of the container. As can be seen from FIGS. 1 and 2, the annular channel  28  is significant in size to accommodate more than just a few droplets of fluid. 
     In the preferred embodiment of the present invention, the tear-back portion  18  of the lid  10  and the straw slot opening  22  are formed in a medial portion of the lid which is not raised, wherein the non-raised medial portion is surrounded on three of its sides by central raised portion  24 . The straw slot opening  22  is formed radially inward of the tear-back portion  18  of the lid  10 , wherein the tear-back portion  18  of the lid  10  includes a protrusion  30  which extends from the upper surface of the lid  10 . The tear-back portion  18  of the lid  10  extends from the annular mounting portion  16  to a trough  32  formed radially inward of the annular mounting portion  16  between the protrusion  30  and straw slot opening  22 . The trough  32  serves as the pivotal hinge axis for the tear-back portion  18  of the lid  10 , so that, as the tear-back portion  18  is torn away from the remaining portion of the lid  10 , the tear-back portion  18  will rotate away from the brim  14  of the cup  12  while pivoting about trough  32 . 
     A flange  34  extends from the edge of the skirt  17  away from the cup  12  on the tear-back portion  18  of the lid  10  to provide a gripping surface for a consumer to grasp and pull in order to tear open tear-back portion  18 . In order to facilitate tearing, a pair of cuts  36  may be formed through the skirt  17  adjacent to flange  34  to provide a starting point for tearing open tear-back portion  18 . In an alternative embodiment of the present invention, a plurality of corrugations  36  may be formed on both sides of protrusion  30 , as shown in FIG. 3, to direct the tearing of tear-back portion  18  in a predetermined manner and prevent accidental and random tear directions to be assumed. The corrugations  36  preclude random tearing by the fact that the lid structure is extremely rigid across the corrugated sections  36  and weak only on the precise line at which the corrugations  36  stop. Therefore, a sharp and accurate tear line is provided along the edge  38  of the corrugations  36  without the disadvantages of a score line which is the most frequently used tear inducing means. The formation of corrugations  36  in the lid  10  provides a simple and efficient method of producing an accurate tear line since the corrugations  36  can be formed along with the rest of the lid  10  and delicate tool adjusting is not required as is required with a score line to avoid cutting through the lid material if the score is too deep or forming an inadequate score line if too shallow. 
     The straw slot opening  22  is formed in a depression  40  within the lid  10 , wherein the depression  40  facilitates the receipt of the end of a straw (not shown) in the straw slot opening  22  as the opening to the depression  40  in the top surface of the lid  10  is larger than the diameter of the straw. The depression  40  includes a pair of sloping side walls  42  and  44  which extend from the top surface of the lid  10  toward a frangible junction  46  at the bottom of the depression  40 , so that the depression  40  has a V-shaped or triangular cross-sectional shape, as can be seen from FIG.  4 . The thickness of the lid material at frangible portion  46  is thinner than the lid material in the other portions of the lid  10  to allow frangible portion  46  to be ruptured by the force exerted by the end of a straw as it is inserted into straw slot opening  22 . As a straw is inserted into straw slot opening  22 , the tapered shape of the depression  40  causes the circular shape of the end of the straw to flatten until the end of the straw deforms into a V-shaped cross-sectional shape similar to that of the depression  40 . Therefore, the end of the straw is deformed into a point as it progresses into depression  40  which acts to assist in piercing frangible portion  46  in addition to the force applied by the straw pushing side walls  42  and  44  away from oneanother. The side walls  42  and  46  further extend between end walls  48  and  50  in depression  40 , wherein end walls  48  and  50  prevent against extended fracture, cracking or tearing of the frangible junction  46  which may be caused by the insertion of the drinking straw into the straw slot opening  22 . Due to the V-shaped configuration of the depression  40 , a momentary countering force is created to center the straw over the frangible portion  46  by side walls  42  and  44 . If the force used to insert the straw is excessive, the end walls  48  and  50  provide a structure which redirects and absorbs the tearing forces to prevent extended tears across the lid  10 . The momentary excessive force will be absorbed by the end walls  48  and  50  such that the radial propagation of the tear will reach the end walls  48  and  50  which causes the radial force to be redirected upwardly which prevents continued tearing of the frangible juncture  46 . 
     The frangible portion  46  is formed at substantially the same time as the remaining structural portions of the lid configuration. That is, a sheet of thermo-deformable material, such as thermoplastic, is placed in a predetermined position with respect to a die element in a known manner for forming lids of this nature. The thermo-deformable material is either previously heated or subsequently heated to a deformable temperature and then vacuum formed over the die element. A suction device draws the thermodeformable material into a depression in the die element to form depression  40 , wherein the thermo-deformable material is drawn into the depression until the desired thickness of the material forming frangible portion  46  at the bottom of the depression is achieved. Therefore, frangible portion  46  is formed at the same time as the rest of the lid configuration without the need for delicate tool adjusting to provide the proper scoring in the lid material as is usually done when forming straw slots. Furthermore, since frangible portion  46  is integrally formed with the rest of the lid  10 , the lid  10  has no openings where the contents of the cup  12  can spill out if the cup  12  is advertently knocked over. While the depression  40  is described above as having a V-shaped cross-sectional shape, it is understood that the depression  40  may comprise any shape which allows the straw slot opening  22  to function with the goals and objectives of the present lid configuration as described herein. 
     Once frangible junction  46  is broken by the end of a straw, the side walls  42  and  44  of depression  40  are separated from oneanother and allow the straw to travel into the cup  12  between the side walls  42  and  44 . As the straw passes between side walls  42  and  44 , the side walls  42  and  44  bend around the straw to conform to the shape of the straw. Therefore, the side walls  42  and  44  provide a close engagement around the inserted straw, which acts to seal the cup lid  10  around the straw to prevent the contents of the cup  12  from spilling out of the straw slot opening  22  between the straw and side walls  42  and  44 . Additionally, each of side walls  42  and  44  included guides  43  and  45 , respectively which aid the consumer in inserting the straw into the depression  40 . 
     The protrusion  30  is shaped such that when the tear-back portion  18  of the lid  10  is opened and pivoted about hinge  32 , the protrusion  30  is received within depression  40  to retain the protrusion in an open position, as shown in FIG.  2 . The width of protrusion  30  is slightly larger than the width of depression  40 , resulting in the end walls  48  and  50  frictionally engaging the end surfaces  52  and  54  of protrusion  30  to hold the protrusion within depression  40 . In order to be received within depression  40 , protrusion  30  includes sloping side surfaces  56  and  58  of a substantially similar slope to that of sloping side walls  42  and  44  of depression  40 , wherein sloping side surfaces  56  and  58  rest adjacent to sloping side walls  42  and  44 , respectively, when protrusion  30  is inserted into depression  40 . In the preferred embodiment of the present invention, protrusion  30  has a substantially trapezoidal cross-sectional shape, as illustrated best in FIG.  4 . However, protrusion  30  may be triangular or any other shape which allows the protrusion to be positioned within depression  40  without rupturing frangible juncture  46 . 
     By forming protrusion  30  having a substantially similar shape as depression  40 , the protrusion  30  will not engage the sloping side walls  42  and  44  of depression  40  and cause frangible juncture  46  to be broken. Therefore, the straw slot opening  22  remains unaffected and frangible juncture  46  remains intact when the straw slot depression  40  is used to retain the tear-back portion  18  of the lid  10  in an open position. Even if frangible juncture  46  is broken by inserting a straw into depression  40 , end walls  48  and  50  of depression  40  will still function equivalently by frictionally engaging protrusion  30  to retain the tear-back portion  18  in the open position. Accordingly, the prior use of one of the drink-thru features of the lid  10  will not affect later use of the other drink-thru feature by a consumer. 
     A recess  60  is also formed in the lid configuration radially inward of the depression  40  for receiving the mounting portion  16  of the lid  10  when the tear-back portion  18  is retained in its open position. The lid configuration is further designed such that a plurality of lids  10  may be positioned together in a stacked relationship, as shown in FIG.  5 . 
     In one embodiment of the lid configuration of the present invention, a plurality of inwardly projecting interrupted beads  62  are formed about the periphery of the skirt  17  to assist in retaining the lid  10  on the rim  14  of the cup  12 . The beads  62  extend radially inward further than the remaining portions of skirt  17 , causing the mounting portion  16  of the lid  10  to engage the rim  14  of the cup  12  more tightly in the portions of the skirt  17  where the beads  62  are formed. This causes a greater frictional engagement between the lid  10  and the rim  14  of the cup  12  at beaded portions  62  which assists in retaining the lid  10  on the rim  14  of the cup  12 . Greater frictional engagement between the lid  10  and cup  12  is especially useful in retaining the lid  10  in place when an upward force is applied on flange  34  to tear open tearback portion  18 . For this reason, beads  62  of a first predetermined length are formed in the skirt  17  at least on both sides of tear-back portion  18  to retain the lid  10  on the rim  14  of the cup  12  as a force trying to remove the lid  10  will be exerted on that area of the lid  10  when tear-back portion  18  is opened. Furthermore, two spaced-apart beads  64  of a second predetermined length, shorter than the beads  62  of the first predetermined length, are formed in the skirt  17  connected to tear-back portion  18 . The beads  64  assist in retaining the tear-back portion  18  of the lid  10  on the rim  14  of the cup  12 , especially when closing tear-back portion  18  after it has already been opened. 
     FIG. 6 shows a cross-sectional view of a die element  70  which may be used to form the interrupted beads  62  and  64  of the lid illustrated in FIG.  1 . This die  70  is used along with otherwise conventional thermoforming equipment in a lid thermoforming process such as is conventionally performed to create the remaining features molded into the plastic disposable cup lids  10 . Further, the die  70  may be readily added to the present thermoforming cup dies for the formation of disposable cup lids. The die  70  includes an outer circumferential projection  72  which is used to form the mounting portion  16  and skirt  17  of the lid  10 . FIG. 7 shows an enlarged view of area A on the circumferential projection  72  of FIG.  7 . The projection  72  includes a plurality of indentations  74  which are used to form interrupted beads  62  and  64 , wherein vacuum passageways  76  are formed in the die  70  extending from indentations  74  to a suction device (not shown) to draw the thermo-deformable material in the indentations  74 . 
     FIG. 8 shows a die element  80  which may be used to form the remaining portions of the lid configuration of the present invention, wherein die element  80  may be used in conjunction with die element  70  to form lid  10 . The die  80  includes recess  82  designed to form straw slot depression  40 , wherein a groove  84  is formed at the bottom of recess  82  to form frangible portion  46 . A vacuum passageway, similar to that of vacuum passageway  76 , is formed at the nadir of groove  84  to draw the thermo-deformable material into recess  82 . The die  80  also includes recesses  86  and  88  to form trough  32  and recess  60  in the lid  10 , respectively. Additionally, die  80  includes an aperture  90  for receiving an alignment projection  78  from die  70  in order to ensure the interrupted beads  62  and  64  are formed in the proper locations with respect to the remaining features of the lid formed by die  80 . 
     As can be seen from the foregoing, a cup lid formed in accordance with the present invention provides a simpler structure to manufacture due the straw slot depression  40  serving dual functions of providing a straw slot opening as well as retaining the tear-back portion  18  of the lid in an open position. Therefore, only one depression needs to be formed in the cup lid to accomplish both functions. Furthermore, forming a cup lid in accordance with the present invention provides a straw slot and tear-open flap which can be molded at substantially the same time as the remaining features of the lid without the need for precise tooling to perform scoring in the lid. 
     While the present invention has been described with reference to a preferred embodiment, it should be appreciated by those skilled in the art that the invention may be practiced otherwise than as specifically described herein without departing from the spirit and scope of the invention. It is, therefore, to be understood that the spirit and scope of the invention be limited only by the appended claims.