Abstract:
A stamp die assembly for a self inking stamp in which the die plate having printing indicia thereon is easily removable from the die frame. There are at least two locking bars on the die frame that engage in locking relationship at least two positioning tabs on the die plate. Locking tabs on the positioning tabs engage in a locking relationship the locking bars to securely attach the die plate to the die frame. The locking tabs are flexible so that when a force is applied to them they can be flexed to an unlocking position thereby releasing the die plate from the die frame.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to hand stamps and more particularly to a self-inking hand stamp. Self inking stamps are one type of hand stamp that are used to create ink impressions on paper or other materials. The self-inking stamps allow the user to continuously stamp pieces of paper or other materials by merely continuously depressing the operating handle. The handle actuates a reciprocating die frame that has a die plate with the printing indicia thereon. The die plate contacts an ink pad to be re-inked each time an impression is made. Generally the die plate reciprocates in a stamp frame to contact the ink pad and then rotates 180° to contact the paper surface on which it prints the impression. 
     One example of a self inking stamp is illustrated in U.S. Pat. No. 7,124,684. It can be seen in the &#39;684 patent that there is an actuating handle that when depressed causes the stamp insert and printing plate to reciprocate between the raised inking position in which the printing plate contacts an ink pad, and the lowered or printing position in which the printing plate contacts the printing surface. Another example of a self inking stamp is illustrated in U.S. Pat. No. 7,011,024. This patent also illustrates a self-inking stamp that has a removable stamp die that is detachably mounted to a bracket that reciprocates when the handle of the stamp is actuated. As such it can be seen that self inking stamps are known in the art. The present invention is related to these self inking stamps but is directed to a uniquely removable die plate that allows the user to easily replace one die plate with another. This allows the user to replace a worn die plate or a different die plate with another impression thereon without throwing out the hand stamp. 
     SUMMARY OF THE INVENTION 
     The self-inking stamp has a stationary stamp frame on which is mounted an actuating handle that is operatively connected to a reciprocating die frame. The die frame has the die plate with a printing plate mounted on its bottom surface to transfer the image from the printing plate to the printing surface. An ink pad is mounted in the stamp frame so that the printing plate attached to the die plate contacts the ink pad each time the actuating handle is forced by means of springs to its upward position. In this manner continuous printing can be accomplished by the user. 
     The die plate has an opposite pair of positioning tabs that are received by locking bars on the die frame so that the tabs are locked in place by locking tabs or barbs located on the positioning tabs. The positioning tabs are flexible so that they snap in place around the locking bars on the die frame, yet can be released by the user applying pressure to the tabs to spread them apart so that they can be released from the locking bars. The tops of the tabs are tapered or beveled so that they will allow for some misalignment when the stamp frame and die frame is initially positioned and pushed onto the die plate so that it is easier for the user to attach the die plate to the die frame. This design allows the user to easily change die plates so that one stamp can be used for many stamping images by merely changing the die plates. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the self-inking stamp shown in dotted lines with the die frame and die plate in the top position to contact the ink pad within the stamp frame. 
         FIG. 2  is a perspective vie of the self-inking stamp shown in dotted lines with the die frame and die plate in the bottom or printing position with the actuating handle in the depressed position. 
         FIG. 3  is a top front perspective exploded view showing the die frame released from the die plate. 
         FIG. 4  is front top perspective view of the assembled die frame and die plate. 
         FIG. 5  is a cross sectional view taken along line  5 - 5  of  FIG. 3  of the die frame and pivot pin. 
         FIG. 6  is a cross section view taken along line  6 - 6  of  FIG. 3  of the die plate and tabs. 
         FIG. 7  is a cross section view taken along line  7 - 7  of  FIG. 4  of the die frame, die plate and tabs in the locked, assembled position ready for printing. 
         FIG. 8  is a front top perspective view of an alternative embodiment of the die plate having a pre-inked pad for providing ink to the printing surface of the die plate. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning first to  FIG. 1 , there is illustrated a hand stamp  10  in dashed lines that incorporates the present invention. The stamp  10  is a self inking stamp as described above and has an operating mechanism as previously taught in the prior art. There is an actuating handle  12  and can be provided with a locking mechanism (not illustrated) that allows the user to lock the actuating handle in the lowered or depressed position. Various locking mechanisms are taught in the prior art and can be self releasing or require the user to manually operate a slide or button to release the actuating handle  12 . The stamp  10  has a front frame  16 , a rear frame  18  and frame sides  20 . An ink pad slot  22  is provided to receive an ink pad. 
     A die frame  24  is mounted to a reciprocating mechanism that is mounted in the actuating handle  12 . The reciprocating mechanism causes the die frame  24  to rotate 180° from the raised or upper position in which the die frame faces the ink pad in the slot  22  and a lowered position in which the die frame  24  rotates and faces the printing surface, such as illustrated in  FIG. 2 . 
     The die frame  24  is most clearly illustrated in  FIG. 3 . There is a right support  26  and an opposite left support  28 . A pivot rod  30  passes through the left and right supports  26 ,  28  and provides the pivot point about which the die frame  24  rotates from its raised to lowered positions. There is a front locking bar  32  and a rear locking bar  34  located respectively at the front and rear of the die frame  24 . The locking bars  32  and  34  have a height “H” that will be described in greater detail below. 
     Also illustrated in  FIG. 3  is a die plate  36  that has a front  38 , a rear  40 , and opposite sides  42 ,  44 . The die plate  36  also has a top surface  46  and a bottom surface  48 . Attached to the bottom surface  48  is a printing plate  49  that has printing indicia thereon. The printing plate  49  is of the type commonly used in stamps and is generally made of rubber with raised printing indicia that contacts the ink pad when the die frame is rotated into its raised position as illustrated in  FIG. 1 . 
     Mounted on or integrally formed with the die plate  36  is an upstanding front positioning tab  50  and an upstanding rear positioning tab  52 . There are front locking tabs  54  (seen in  FIGS. 6 and 7 ) that extend tapering inwardly and rear locking tabs  56  as seen in  FIGS. 3, 6 and 7  that also extend tapering inwardly. The locking tabs  54 ,  56  have a lower shoulder  57 . The top surface of the front and rear positioning tabs  54 ,  56  have a tapered top edge  53 . 
     To attach the die plate  36  to the die frame  24  the user places the die plate  36  with the printing plate  49  in the down or printing position inside the area defined by the front frame  16 , rear frame  18  and frame sides  20 . The user pushes down on the actuating handle  12  which forces the die frame  24  downward. The front and rear locking bars  32 ,  34  strike the tapered top edge  53  of the front and rear positioning tabs  50 ,  52  respectively. The distance between the front locking bar  32  and rear locking bar  34  is slightly less than the distance between the front positioning tab  50  and rear positioning tab  52  to allow the locking bars  32 ,  34  to enter the space between the positioning tabs  50 ,  52 . The tapered top edge  53  on the positioning tabs further assists in positioning the locking bars  32 ,  34  between the positioning tabs  50 ,  52 . The positioning tabs  50 ,  52  are made from a flexible material, such as plastic, to allow them to flex outwardly when an outward force is applied to them, yet have a memory that will cause the tabs  50 ,  52  to snap back to their original position when the force is removed. 
     The downward force applied to the actuating handle  12  pushes the locking bars  32 ,  34  against the tapering top surfaces of the locking tabs  54 ,  56 . This causes the front positioning tab  50  and rear positioning tab  52  to flex outward allowing the front locking bar  32  and rear locking bar  34  to slide over the top tapered surface of the locking tabs  54 ,  56  until the top of the front locking bar  32  and top of the rear locking bar  34  slides past the shoulder  57  at which point the front and rear positioning tabs  50 ,  52  snap back into their original position with the front and rear locking bars  32 ,  34  locked in place below the shoulder  57  of the locking tabs  54 ,  56  respectively as seen in  FIG. 7 . Thus the die plate  36  is firmly locked in place against the die frame  24 . 
     To release the die plate  36  from the die frame  24 , the user grabs the top edges  53  of the front and rear positioning tabs  50 ,  52  and spreads them outwardly. This releases the locking tabs  54 ,  56  from engagement with the top of the locking bars  32 ,  34  allowing the die plate  36  to be released from the die frame. The user can then attach another die plate with other printing indicia thereon to the die frame  24  rather than replacing the entire hand stamp  10 . Also when the printing plate  49  wears out, it can be replaced without replacing the entire stamp  10 . Inventory is reduced as the user only needs to store differing die plates  36  rather than an entire stamp  10 . 
       FIG. 8  illustrates an alternate embodiment of a die plate  58  having a printing plate or surface  60 . This embodiment uses a pre-inked thermoplastic foam that allows ink to pass through certain areas of the foam and not through others, thereby forming the image that is to be printed. Examples of this technology are illustrated in U.S. Pat. No. 5,942,312 and U.S. Pat. No. 6,968,781, both patents incorporated herein by reference. Thus, the ink pad placed in the slot  22  is eliminated. In other respects the die plate  58  is attached to the die frame  24  in the same manner as previously described in the first embodiment. 
     Thus there has been provided a removable die plate for self-inking stamps. While the invention has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims.