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 is a movable latch on the die plate that is received by a catch or slot in the die frame to lock the die plate to the die frame. By pushing on a push button the catch is moved from the locked position to the unlocked position in which the latch is released from the catch. A spring returns the latch to the original or locked position.

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 die plate with a different 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. In another embodiment the die plate has an ink supply within the die plate so that the printing plate is continuously supplied with ink without the need for contacting a separate ink pad. 
     The die plate has an opposite pair of latches that are received in slots on cross braces on the die frame so that the latches are locked in place by in the slots by locking tabs or barbs located on the latches. The latches are spring loaded so that they snap in place in the slots on the cross braces on the die frame, yet can be released by the user applying pressure to the latches to move them out of engagement with the slots so that they can be released from the slots. The tops of the latches are tapered or beveled so that they will allow for some misalignment when the 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 latches 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  which 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 which 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. The front frame  16  and rear frame  18  have a thumb cutout or indentation  23 . 
     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 cross brace  32  and a rear cross brace  34  located respectively at the front and rear of the die frame  24 . The front cross brace  32  has a front slot or opening  37  and the rear cross brace  34  has a rear slot or opening  39  disposed at the center of their respective braces. Although the term slot  37  and  39  is used to describe this element, it also may be referred to herein as a “catch”. The front and rear cross braces  32 ,  34  are connected by a bridging member  35 . The cross braces  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 retaining member  50  and an upstanding rear retaining member  52 . There is a front latch  56  and a rear latch  58 . The top surface of the latches  56  and  58  taper downwardly and out as clearly seen in  FIGS. 6 and 7 . The latches  56  and  58  have a lower shoulder  59 . 
     The front latch  56  is mechanically connected through a slot  60  in the front retaining member  50  to a front push button  60 . A front spring  64  pushes the front latch  56  out from the center of the die plate  36  so that the front pushbutton  62  is pushed outward. The front spring  64  is retained on the die plate  36  by means of a stop  66 . The rear latch  58  is likewise mechanically connected through a slot  68  in the rear retaining member  52  to a rear pushbutton  70 . A rear spring  72  pushes the rear latch  58  out from the center of the die plate  36  so that the rear pushbutton  72  is pushed outward. The rear spring  72  is retained on the die plate  36  by means of a stop  74 . By the user pushing on the pushbuttons  62  and  70  with sufficient force to overcome the spring forces  64  and  72  respectively, the user can slide the front and rear latches  56  and  58  horizontally over the top surface  46  within the range of movement provided by the pushbuttons  62  and  70  and their respective mechanical connections to the latches  56  and  58 . 
     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 outer edge of the slots or catches  37  and  39  strike the tapered top edge  53  of the front and rear latches  56 ,  58  respectively. The size of the front and rear latches  56 ,  58  is smaller than the slots  37 ,  39  to allow the latches  56 ,  58  to enter the slots  37 ,  39  respectively. The tapered top edge  53  on the latches  56 ,  58  further assists in positioning the latches  56 ,  58  within the slots  37 ,  39 . 
     The downward force applied to the actuating handle  12  pushes the latches  56 ,  58  against the slots  37 ,  39  in the front cross brace  32  and rear cross brace  34 . This causes the front latch  56  and rear latch  58  to slide inward allowing the front retaining member  50  and rear retaining member  52  to slide over the top tapered surface  53  of the latches  56 ,  58  until the top of the front retaining member  50  and top of the rear retaining member  52  slides past the shoulder  59  at which point the front and rear latches spring back into their original position due to the force exerted by the springs  64  and  72  with the front and rear latches  56 ,  58  locked in place below the shoulder  59  of the latches  56 ,  58  respectively as seen in  FIG. 7 . The height “H” of the front and rear cross braces  32 ,  34  is sufficient to allow the front and rear retaining members  50 ,  52  to fit underneath the height “H”. 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 inserts his fingers through the front and rear indents  23  and pushes the front pushbutton  62  and rear pushbutton  70  inwardly. This pushes the front and rear latches  56 ,  58  inward so that the shoulder  59  clears the front cross brace  32  and rear cross brace  34 . The die plate is thus released from the die frame  24 . 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 . 
     It should be noted that by pushing inward on the front pushbutton  62  and rear pushbutton  70 , the die plate  36  can be attached to the die frame  24 . When the force to the pushbuttons is released, the latches  56 ,  58  will lock the die plate  36  to the die frame  24 . This process is the reverse of the process used to remove the die plate described above. 
     The embodiment illustrates slots  37 ,  39  in the die frame  24  to receive the front and rear latches  56 ,  58 , it is readily apparent that the slots can be replaced by any member that acts as a catch such as a cross brace or cross bar or similar structure that receives the latches  56 ,  58  in locking engagement. 
     Although the above described embodiment illustrates two latches to secure the die plate  36  to the die frame  24 , it can be built using only one moveable latch. In this alternate embodiment one of the latches will be stationary and secure one side of the die plate to the frame while only the other latch will move into and out of engagement with the cross brace. 
       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.