Abstract:
A reusable tamper-evident envelope includes a first substrate, a second substrate superimposed on the first substrate, at least one auxiliary substrate superimposed on and joined along one edge to the second substrate, and at least one seal along all but one edge joining the first substrate to the second substrate. Each auxiliary substrate is spaced a user-defined distance from the top edge of the first substrate. A perforation line, extending from the left side to the right side of both the first substrate and second substrates facilitate removal of a portion of the respective substrates. After an item is placed into the envelope, the user-activated seal along the remaining edge joins the first substrate to the second substrate. Subsequent uses are possible by removing portions of the first substrate and second substrate along the perforation lines and activating the auxiliary user-activated seal along the auxiliary substrate joining the first substrate to the second substrate.

Description:
FIELD OF THE INVENTION 
   The present invention relates, in general, to a flexible bag and in particular, to a heat-sealed, tamper indicating envelope. 
   BACKGROUND OF THE INVENTION 
   Protecting the contents of an envelope from tampering is a very old problem. Historical methods of producing a tamper-evident envelope used a seal imprinted into candle wax to indicate the sender sealed the envelope and no tampering had occurred en route. Since these early methods, more sophisticated methods have developed. It is well known that banks, government agencies, and businesses ship important items from one location to another. For many of these items, the shipper wants to know whether the item has been tampered with after being placed into an envelope or bag. Modern tamper-evident envelopes use a plastic or paper sheet material for the envelope, with a pre-formed seal along all but one marginal edge. After an item is placed inside the envelope, the user activates the user-activated seal, sealing the envelope. 
   Upon opening the tamper-evident envelope, the plastic sheet material tears, giving a clear indication of tampering. The tamper-evident envelope is then discarded. Thus, each time an object is placed in a tamper-evident envelope, a new envelope must be used. 
   U.S. Pat. No. 4,733,817, entitled “ENVELOPE SYSTEM WITH MULTIPLE POCKETS” discloses an envelope comprising two or more pockets. In an alternate embodiment, a perforation line separates each pocket. One adhesive containing flap is provided for each pocket to secure the contents in the pocket individually. Each pocket is used only once. The envelope system may be used multiple times if a perforation line is not present, and at least one unused pocket is sent along with the contents sealed in one of the pockets. The present invention is not limited in this regard. U.S. Pat. No. 4,733,817 is hereby incorporated by reference into the specification of the present invention. 
   U.S. Pat. No. 5,950,916, entitled “SECURITY ENVELOPE” discloses a reusable envelope. An elongated fold-over flap is used with a plurality of adhesive layers to permit the security envelope to be reused. The user activates an unused adhesive layer farthest from the body of the envelope to seal the envelope. Upon reaching the destination, the recipient tears the fold-over flap along a pair of perforation lines separating the activated adhesive layer and an adjacent inactivated adhesive layer. Subsequent uses of the envelope are possible by activating each remaining adhesive layer in turn. The elongated fold-over flap creates a large unsecured space. Covert entry is possible by exploiting this unsecured area. The present invention is not limited in this regard. U.S. Pat. No. 5,950,916 is hereby incorporated by reference into the specification of the present invention. 
   U.S. Pat. No. 6,032,854, entitled “MULTIPLE-USE SEALABLE PACKAGES” discloses an improved tamper-evident container comprising a single perforation line between a pair of user-activated seals. The perforation line creates a line of weakness between the two adhesive layers, only one of which is activated. After the first use, the container may be used again by activating the second adhesive layer. The fold-over flap creates a large unsecured space. Covert entry is possible by exploiting this unsecured area. The present invention is not limited in this regard. U.S. Pat. No. 6,032,854 is hereby incorporated by reference into the specification of the present invention. 
   U.S. Pat. No. 6,435,404, entitled “RETURN MAILER” discloses a reusable mailing envelope comprising a plurality of adhesives deposited on a fold-over flap and a transparent sleeve for viewing insertable mailing indicia cards. As noted above, the fold-over flap creates a large unsecured space facilitating covert entry into the interior of this unsecured area. U.S. Pat. No. 6,435,404 is hereby incorporated by reference into the specification of the present invention. 
   There exists a need for a multiple use tamper-evident envelope with improved resistance to tampering. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a reusable tamper-evident envelope with enhanced protection against unauthorized entry. 
   A tamper-evident envelope according to the present invention has a first substrate and a second substrate superimposed upon the first substrate. The first substrate and the second substrate have a left marginal edge, a right marginal edge, a bottom marginal edge, and a top marginal edge. 
   The first substrate has at least one linear perforation line, spaced a user-definable distance from the top marginal edge. The second substrate has at least one nonlinear perforation line, spaced a user-definable distance from the top marginal edge. The nonlinear perforation line has two upper portions and a lower portion. The lower portion of the nonlinear perforation line in the second substrate extends farther from the top marginal edge than a corresponding collocated linear perforation line in the first substrate. All perforation lines extend from the left marginal edge to the right marginal edge. 
   At least one auxiliary substrate is superimposed on the second substrate, and has a bottom marginal edge and a top marginal edge. The top marginal edge of the at least one auxiliary substrate is aligned with the two upper portions of the corresponding nonlinear perforation line in the second substrate. An auxiliary seal along the bottom marginal edge of each auxiliary substrate and the second substrate joins the auxiliary substrate to the second substrate. 
   At least one seal along the left marginal edge, the right marginal edge, and the bottom marginal edge of the first substrate and the second substrate joins the first substrate to the second substrate. After an item is placed into the envelope, the envelope is sealed by activating the at least one user-activated seal along the remaining marginal edge. 
   The recipient can open the tamper-evident envelope by tearing the first substrate and the second substrate along the perforation line closest to the top marginal edge. 
   After a subsequent item is placed into the envelope, the envelope is sealed by activating the at least one user-activated auxiliary seal along the top marginal edge of the at least one auxiliary substrate. 
   In the preferred embodiment, the first substrate and the second substrate are made of tear and impact resistant plastic, and the seal and auxiliary seal are a heat weld seal. 
   In a first alternate embodiment, a portion of the first substrate extends beyond the second substrate. A perforation line allows the portion of the first substrate extending beyond the second substrate to be removed. In an alternate first alternate embodiment, at least one identifier is deposited on the portion of the first substrate extending beyond the second substrate matching at least one indicia deposited on the tamper-evident envelope. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view of a typical prior art envelope; 
       FIG. 2  is a perspective view of the present invention; 
       FIG. 3  is a perspective view of a first alternate embodiment of the present invention; and 
       FIG. 4  is a perspective view of a second alternate embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   Referring to  FIG. 1 , a prior art tamper-evident envelope  1  is shown. Prior art envelopes are constructed of a first substrate  2 , a second substrate  3  superimposed upon the first substrate  2 , a seal  4  along all but one of the marginal edges of the envelope, and a user-activated seal  5  along the remaining marginal edge. The user-activated seal  5  is typically an adhesive seal. 
   Referring to  FIG. 2 , a tamper-evident envelope  10  according to the present invention is shown. The tamper-evident envelope  10  comprises a first substrate  12 , a second substrate  13  superimposed upon the first substrate  12 , at least one auxiliary substrate  14  superimposed upon the second substrate  13 , at least one auxiliary seal  15  along the bottom marginal edge of the auxiliary substrate  14  and the second substrate  13 , at least one seal  16  along all but one marginal edge of the first substrate  12  and second substrate  13 , at least one user-activated seal  17  along the remaining marginal edge of the first substrate  12  and second substrate  13 , and at least one user-activated auxiliary seal  18  along the at least one auxiliary substrate  14 . The first substrate  12 , second substrate  13 , and at least one auxiliary substrate  14  are preferably made of a flexible plastic sheet material. The plastic sheet material is preferably resistant to shear forces and impact forces. Other suitable or equivalent material may be used for the first substrate  12 , the second substrate  13 , and the at least one auxiliary substrate  14 . 
   The first substrate  12  and the second substrate  13  have a left marginal edge, a right marginal edge, a bottom marginal edge, and a top marginal edge. While a generally rectangular tamper-evident envelope is shown, a tamper-evident envelope of the present invention may be made in a variety of shapes, such as square, round, or oblong without deviating from the scope of the invention. 
   Tamper-evident bags of the present invention may be made in any size to suit the object being stored therein. Plastic sheeting used in making the envelope may be clear or opaque, and may contain handles applied thereto for ease of transport. Those persons skilled in the art will recognized that the thickness of the plastic sheet material of the first substrate  12 , the second substrate  13 , and the at least one auxiliary substrate  14  may vary depending on the item typically stored in the tamper-evident envelope  10 . 
   At least one linear perforation line  20  extends from the left marginal edge to the right marginal edge of the first substrate  12 . The at least one linear perforation line  20  is spaced a user-definable distance from the top marginal edge of the first substrate  12 . The number of linear perforation lines equals the number of times the tamper-evident envelope can be reused. 
   At least one nonlinear perforation line  21  extends from the left marginal edge to the right marginal edge of the second substrate  13 . The nonlinear perforation line  21  has a lower portion and two upper portions. The lower portion of the at least one nonlinear perforation line  21  is spaced a user-definable distance from the top marginal edge of the second substrate  13  and its user definable distance is greater than the user-defined distance from the top marginal edge to the linear perforation line  20  contained on the first substrate  12 . Each nonlinear perforation line  21  corresponds to a linear perforation line  20  in the first substrate  12 . 
   In an alternate embodiment, at least one identifier  22  is printed on the first substrate  12 , the second substrate  13 , or both. Typical identifiers  22  include a serial number of the tamper-evident envelope  10 , user instructions, a holographic image, a Radio Frequency Identification tag, and a magnetic strip. Preferably, a portion of the first substrate  12  or the second substrate  13  is treated to allow the user to write on the envelope with a ballpoint pen. 
   At least one auxiliary substrate  14  is superimposed upon the second substrate  13 , and has a top marginal edge and a bottom marginal edge. The top marginal edge of the at least one auxiliary substrate  14  is aligned with the two upper portions of one of the at least one nonlinear perforation line  21 , and joined to the second substrate  13  along the bottom marginal edge of the auxiliary substrate  14  with an auxiliary seal  15 . The auxiliary seal  15  may be a heat weld, a sonic weld, an adhesive weld, any combination thereof, or any equivalent auxiliary seal. 
   At least one user-activated auxiliary seal  18  is applied along the top marginal edge of the auxiliary substrate  14 . The at least one user activated seal  18  preferably is an adhesive seal. The adhesive used in tamper-evident envelope  10  adhesive seals are typically chosen to maintain their adhesion over a wide variety of factors. Typical factors include temperature, solvent, and shear force. 
   In an alternate embodiment, the user-activated auxiliary seal  15  has a plurality of adhesive layers, each offering better adhesion resistance to a different factor and therefore offering improved resistance to tampering. For instance, if three adhesive layers are used, one adhesive layer may have better adhesion resistance to cold temperatures, one adhesive layer may have better adhesion resistance to hot temperatures, and the third adhesive layer may have better adhesion resistance to solvents. 
   When an adhesive is used as the user-activated auxiliary seal  18 , a release layer  24  is preferably used to prevent the adhesive from adhering the first substrate  12  to the second substrate  13  before the user is ready to seal the tamper-evident envelope  10 . 
   In an alternate embodiment, at least one indicia is used in conjunction with the adhesive of the user-activated auxiliary seal  18  to give a visual indication of a tamper. The at least one indicia may be deposited on the second substrate  13 , or the user-activated auxiliary seal  18 . Shear force, such as by stretching, causes a recognizable pattern to emerge, indicating tampering has occurred. 
   To form the interior cavity of the tamper-evident envelope  10 , the second substrate  13  is superimposed upon the first substrate  12  and at least one seal  16  joins the first substrate  12  to the second substrate  13  along the left marginal edge, the right marginal edge, and the bottom marginal edge. The seal  16  may be a heat weld, a sonic weld, an adhesive weld, any combination thereof, or any equivalent seal. 
   At least one user-activated seal  17  is applied along the top marginal edge. After an item is placed into the tamper-evident envelope  10 , the user seals the remaining marginal edge of the first substrate  12  to the second substrate  13 . The at least one user activated seal  17  may be a heat weld, a sonic weld, an adhesive weld, any combination thereof, or any equivalent seal. 
   In an alternate embodiment, the user-activated seal  17  is at least one adhesive seal joining the first substrate  12  to the second substrate  13 . The adhesive used in tamper-evident envelope  10  adhesive seals are typically chosen to maintain their adhesion over a wide variety of factors. 
   In an alternate embodiment, the user-activated seal  16  has a plurality of adhesive layers, each offering better adhesion resistance to a different factor and therefore offering improved resistance to tampering. 
   Those persons skilled in the art will recognize that if an adhesive seal is used for the user-activated seal  16 , the adhesive may be deposited onto the first substrate  12 , the second substrate  13 , or both substrates. 
   When an adhesive is used as the user-activated seal  16 , a release layer  26  is preferably used to prevent the adhesive from adhering the first substrate  12  to the second substrate  13  before the user is ready to seal the tamper-evident envelope  10 . 
   In an alternate embodiment, at least one indicia is used in conjunction with the adhesive of the user-activated seal  16  to give a visual indication of a tamper. The at least one indicia may be deposited on the first substrate  12 , the second substrate  13 , or the user-activated seal  16 . Shear force, such as by stretching, cause a recognizable pattern to emerge, indicating tampering has occurred. 
   Tearing along the linear perforation line  20  and the nonlinear perforation line  21  opens the tamper-evident envelope  10 . After an item is placed into the tamper-evident envelope  10 , a remaining inactivated at least one auxiliary seal  15  is activated to seal the tamper-evident envelope  10  for a subsequent use. 
   The lower portion of the at least one nonlinear perforation line  21  in the second substrate  13 , which extends farther from the top marginal edge than the linear perforation line  20  in the first substrate  12 , allows the at least one user-activated auxiliary seal  18  to join the second substrate  13  to the first substrate  12 . 
   In a first alternate embodiment  30  shown in  FIG. 3 , a portion of the first substrate  32  extends beyond the second substrate  33 . Preferably, a perforation line  34  extends from the left marginal edge to the right marginal edge, allowing the portion of the first substrate  32  extending beyond the second substrate  33  to be removed. 
   In an alternate embodiment, at least one identifier  35  is deposited on the portion of the first substrate  32  extending beyond the second substrate  33 . The identifier  35  may be a serial number of the tamper-evident envelope  30 , user instructions, a holographic image, a Radio Frequency Identification tag, and a magnetic strip. Preferably, one of the identifiers  35  deposited on the portion of the first substrate  32  extending beyond the second substrate  33  is the same as the identifier,  36  deposited on the first substrate  32 , the second substrate  33 , or both. The removable portion of the first substrate  32  provides a receipt for the sending user. 
   In a second alternate embodiment  40  shown in  FIG. 4 , a vertical perforation line  44  splits the portion of the first substrate  42  extending beyond the second substrate  43 , forming a pair of receipts. The vertical perforation line extends from the top marginal edge of the first substrate  42  to the perforation line  45  extending from the left marginal edge to the right marginal edge. Unique identifiers  46  are deposited on each receipt and correspond to identical identifiers  47  and  48  on the tamper-evident envelope  40 . 
   While the preferred embodiments of the invention have been illustrated and described, it will be apparent to those of ordinary skill in the art that various changes and modifications may be made without deviating from the inventive concepts set forth above.