Abstract:
A lever latching system comprising: a housing; a lever having a latch pin fixedly mounted to the lever, the lever being movably mounted to the housing so that the latch pin moves in an arc; and a latch plate movably mounted to the housing for linear movement with respect to the housing, the latch plate comprising a labyrinth for receiving the latch pin.

Description:
REFERENCE TO PENDING PRIOR PATENT APPLICATION 
     This patent application claims benefit of prior U.S. Provisional Patent Application Ser. No. 61/994,179, filed May 16, 2014 by Gyrus ACMI, Inc. (d.b.a. Olympus Surgical Technologies America) and Dennis G. Lamser et al. for ENDOSCOPIC CUTTING FORCEPS WITH JAW CLAMP LEVER LATCHING MECHANISM, which patent application is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to surgical apparatus and methods in general, and more particularly to endoscopic cutting forceps and jaw clamp lever latching mechanisms for use with the same and/or for use with other lever-actuated devices. 
     BACKGROUND OF THE INVENTION 
     Endoscopic cutting forceps are well known in the art. In general, endoscopic cutting forceps comprise a pair of jaws disposed at the distal end of a shaft, a blade cutter configured to reciprocate in the space between the jaws (and hence cut tissue disposed between the pair of jaws), and a handle disposed at the proximal end of the shaft for carrying a lever for actuating the pair of jaws and a trigger for actuating the blade cutter. In some constructions, the endoscopic cutting forceps allow the pair of jaws and the blade cutter to be rotated as a unit about the axis of the shaft, and/or the endoscopic cutting forceps allow the pair of jaws to be electrically energized so as to provide electrocautery function to the endoscopic cutting forceps. 
     In general, it can be convenient to provide a latching mechanism for the lever which actuates the jaws, whereby to allow the jaws to be temporarily locked (or clamped) in a closed position about tissue, e.g., while the blade cutter is actuated to cut the tissue disposed between the clamped jaws. 
     Unfortunately, current latching mechanisms for endoscopic cutting forceps tend to be mechanically complex and hence difficult and/or expensive to manufacture. 
     Thus there is a need for a new and improved latching mechanism for an endoscopic cutting forceps wherein the latching mechanism is mechanically simple and hence easy and inexpensive to manufacture. 
     There is also a need for a new and improved latching mechanism for the actuating levers of other surgical instruments and/or other lever-actuated devices wherein the latching mechanism is mechanically simple and hence easy and inexpensive to manufacture. 
     SUMMARY OF THE INVENTION 
     The present invention provides a new and improved latching mechanism for an endoscopic cutting forceps wherein the latching mechanism is mechanically simple and hence easy and inexpensive to manufacture. 
     The present invention also provides a new and improved latching mechanism for the actuating levers of other surgical instruments and/or other lever-actuated devices wherein the latching mechanism is mechanically simple and hence easy and inexpensive to manufacture. 
     In one form of the present invention, there is provided a lever latching system comprising: 
     a housing; 
     a lever having a latch pin fixedly mounted to said lever, said lever being movably mounted to said housing so that said latch pin moves in an arc; and 
     a latch plate movably mounted to said housing for linear movement with respect to said housing, said latch plate comprising a labyrinth for receiving said latch pin. 
     In another form of the present invention, there is provided a lever latching system comprising: 
     a housing; 
     a lever pivotally mounted to said housing at a pivot point, and a latch pin fixedly mounted to said lever at a location offset from said pivot point; and 
     a latch plate movably mounted to said housing for linear movement with respect to said housing, said latch plate comprising a labyrinth for receiving said latch pin. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first unit; 
     a second unit comprising a latch pin, said second unit being movably mounted to said first unit so that said latch pin moves in a prescribed motion; 
     a selector plate movably mounted to said first unit; and 
     a latch plate comprising a labyrinth for selectively receiving said latch pin, said latch plate being movably mounted to said selector plate; 
     wherein said latch plate moves linearly relative to said selector plate. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first member; 
     a second member comprising a latch pin, said second member being movably mounted to said first member so that said latch pin moves in a prescribed motion; 
     a selector plate movably mounted to said first member; 
     a latch plate movably mounted to a selector plate and comprising a labyrinth for selectively receiving said latch pin; 
     a spring secured to said selector plate and engaging said latch plate for biasing said latch plate with respect to said selector plate; 
     wherein said selector plate moves said latch plate between an engaged position wherein said labyrinth intersects said prescribed motion and a disengaged position wherein said labyrinth does not intersect said prescribed motion. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first unit; 
     a second unit comprising a latch pin, said second unit being movably mounted to said first unit so that said latch pin moves in a prescribed motion; 
     a selector plate movably mounted to said first unit; and 
     a latch plate comprising a labyrinth for selectively receiving said latch pin, said latch plate being movably mounted to said selector plate; 
     wherein said latch plate comprises an integral spring for biasing said latch plate relative to said selector plate. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first component comprising a latching pin movable in a prescribed motion; and 
     a second component comprising a selector plate that moves a latch plate having a labyrinth between an engaged position wherein said labyrinth intersects said prescribed motion and a disengaged position wherein said labyrinth does not intersect said prescribed motion, said second component comprising a latch spring secured to said selector plate for biasing said latch plate with respect to said selector plate. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first unit; 
     a second unit; 
     said first unit and said second unit being movably mounted relative to one another; 
     a latch pin fixedly mounted to one of said first unit and said second unit; and 
     a latch plate movably mounted to the other of said first unit and said second unit for linear movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first unit fixedly mounted to a handpiece; 
     a second unit; 
     said first unit and said second unit being movably mounted relative to one another; 
     a latch pin fixedly mounted to one of said first unit and said second unit; and 
     a latch plate movably mounted to the other of said first unit and said second unit for linear movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first unit; 
     a second unit pivotably mounted to the first unit; 
     a latch pin fixedly mounted to one of said first unit and said second unit; and 
     a latch plate movably mounted to the other of said first unit and said second unit for linear movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first unit; 
     a second unit; 
     said first unit and said second unit being movably mounted relative to one another; 
     a latch pin fixedly mounted to one of said first unit and said second unit; and 
     a latch plate movably mounted to the other of said first unit and said second unit for non-linear and non-pivotal movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first unit; 
     a second unit; 
     said first unit and said second unit being movably mounted relative to one another; 
     a latch pin fixedly mounted to one of said first unit and said second unit; and 
     a latch plate movably mounted to the other of said first unit and said second unit for non-pivotal movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a lever latching system comprising:
         a housing connected to the mechanism to be operated;   a lever connected to the mechanism to be operated and pivotally mounted to said housing at a pivot point, and a latch pin fixedly mounted to said lever at a location offset from said pivot point; and   a latch plate movably mounted to said housing for linear movement with respect to said housing, said latch plate comprising a labyrinth for receiving said latch pin;       

     moving said lever so that said latch pin causes said latch plate to move with respect to said housing so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving said lever so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a lever latching system comprising:
         a housing connected to the mechanism to be operated;   a lever connected to the mechanism to be operated and having a latch pin fixedly mounted to said lever, said lever being movably mounted to said housing so that said latch pin moves in an arc; and   a latch plate movably mounted to said housing for linear movement with respect to said housing, said latch plate comprising a labyrinth for receiving said latch pin;       

     moving said lever so that said latch pin causes said latch plate to move with respect to said housing so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving said lever so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first unit connected to the mechanism to be operated;   a second unit connected to the mechanism to be operated and comprising a latch pin, said second unit being movably mounted to said first unit so that said latch pin moves in a prescribed motion;   a selector plate movably mounted to said first unit; and   a latch plate comprising a labyrinth for selectively receiving said latch pin, said latch plate being movably mounted to said selector plate;   wherein said latch plate moves linearly relative to said selector plate;       

     moving said second unit so that said latch pin causes said latch plate to move with respect to said first unit so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving said second unit so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first unit connected to the mechanism to be operated;   a second unit connected to the mechanism to be operated and comprising a latch pin, said second unit being movably mounted to said first unit so that said latch pin moves in a prescribed motion;   a selector plate movably mounted to said first unit; and   a latch plate comprising a labyrinth for selectively receiving said latch pin, said latch plate being movably mounted to said selector plate;   wherein said latch plate comprises an integral spring for biasing said latch plate relative to said selector plate;       

     moving said second unit so that said latch pin causes said latch plate to move with respect to said first unit so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving said second unit so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first member connected to the mechanism to be operated;   a second member connected to the mechanism to be operated and comprising a latch pin, said second member being movably mounted to said first member so that said latch pin moves in a prescribed motion;   a selector plate movably mounted to said first member;   a latch plate movably mounted to a selector plate and comprising a labyrinth for selectively receiving said latch pin;   a spring secured to said selector plate and engaging said latch plate for biasing said latch plate with respect to said selector plate;   wherein said selector plate moves said latch plate between an engaged position wherein said labyrinth intersects said prescribed motion and a disengaged position wherein said labyrinth does not intersect said prescribed motion;       

     moving said second member so that said latch pin causes said latch plate to move with respect to said first member so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving said second member so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first component connected to the mechanism to be operated and comprising a latching pin movable in a prescribed motion; and   a second component connected to the mechanism to be operated and comprising a selector plate that moves a latch plate having a labyrinth between an engaged position wherein said labyrinth intersects said prescribed motion and a disengaged position wherein said labyrinth does not intersect said prescribed motion, said second component comprising a latch spring secured to said selector plate for biasing said latch plate with respect to said selector plate;       

     moving said first component so that said latching pin causes said latch plate to move with respect to said second component so that said latching pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving said first component so that said latching pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first unit connected to the mechanism to be operated;   a second unit connected to the mechanism to be operated;   said first unit and said second unit being movably mounted relative to one another;   a latch pin fixedly mounted to one of said first unit and said second unit; and a latch plate movably mounted to the other of said first unit and said second unit for linear movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin;       

     moving one of said first unit and said second unit so that said latch pin causes said latch plate to move with respect to the other of said first unit and said second unit so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving one of said first unit and said second unit so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first unit connected to the mechanism to be operated and fixedly mounted to a handpiece;   a second unit connected to the mechanism to be operated;   said first unit and said second unit being movably mounted relative to one another;   a latch pin fixedly mounted to one of said first unit and said second unit; and   a latch plate movably mounted to the other of said first unit and said second unit for linear movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin;       

     moving one of said first unit and said second unit so that said latch pin causes said latch plate to move with respect to the other of said first unit and said second unit so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving one of said first unit and said second unit so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first unit connected to the mechanism to be operated;   a second unit connected to the mechanism to be operated and pivotably mounted to the first unit;   a latch pin fixedly mounted to one of said first unit and said second unit; and   a latch plate movably mounted to the other of said first unit and said second unit for linear movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin;       

     moving one of said first unit and said second unit so that said latch pin causes said latch plate to move with respect to the other of said first unit and said second unit so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving one of said first unit and said second unit so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first unit connected to the mechanism to be operated;   a second unit connected to the mechanism to be operated;   said first unit and said second unit being movably mounted relative to one another;   a latch pin fixedly mounted to one of said first unit and said second unit; and   a latch plate movably mounted to the other of said first unit and said second unit for non-linear and non-pivotal movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin;       

     moving one of said first unit and said second unit so that said latch pin causes said latch plate to move with respect to the other of said first unit and said second unit so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving one of said first unit and said second unit so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a method for operating a mechanism having a first state and a second state, the method comprising: 
     providing a latching system comprising:
         a first unit connected to the mechanism to be operated;   a second unit connected to the mechanism to be operated;   said first unit and said second unit being movably mounted relative to one another;   a latch pin fixedly mounted to one of said first unit and said second unit; and   a latch plate movably mounted to the other of said first unit and said second unit for non-pivotal movement with respect to said other of said first unit and said second unit, said latch plate comprising a labyrinth for receiving said latch pin;       

     moving one of said first unit and said second unit so that said latch pin causes said latch plate to move with respect to the other of said first unit and said second unit so that said latch pin is disposed at a latched position within said labyrinth, whereby to cause the mechanism to transition from its first state to its second state and maintain the mechanism in its second state; and 
     moving one of said first unit and said second unit so that said latch pin moves out of its latched position within said labyrinth, whereby to cause the mechanism to transition from its second state to its first state. 
     In another form of the present invention, there is provided a latching system comprising: 
     a first unit; 
     a second unit comprising a latch pin, said second unit being movably mounted to said first unit so that said latch pin moves in a prescribed motion; 
     a selector plate movably mounted to said first unit; and 
     a latch plate comprising a labyrinth for selectively receiving said latch pin, said latch plate being movably mounted to said selector plate; 
     wherein said latch plate comprises an integral spring for biasing said latch plate relative to said first unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects and features of the present invention will be more fully disclosed or rendered obvious by the following detailed description of the preferred embodiments of the invention, which is to be considered together with the accompanying drawings wherein like numbers refer to like parts, and further wherein: 
         FIGS. 1-26  are schematic views showing a novel endoscopic cutting forceps formed in accordance with the present invention, wherein the novel endoscopic cutting forceps comprise a novel jaw clamp lever latching mechanism formed in accordance with the present invention, with  FIGS. 1-16  generally showing the general features of the novel endoscopic cutting forceps and  FIGS. 17-26  generally showing the novel jaw clamp lever latching mechanism of the novel endoscopic cutting forceps; and 
         FIGS. 27-38  are schematic views showing exemplary operation of the novel jaw clamp lever latching mechanism of the endoscopic cutting forceps of  FIGS. 1-26 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Looking first at  FIGS. 1-4 , there is shown novel endoscopic cutting forceps  5  which comprise one preferred embodiment of the present invention. 
     The Novel Endoscopic Cutting Forceps in General 
     Endoscopic cutting forceps  5  generally comprise a pair of jaws  10  disposed at the distal end of a shaft  15 , a blade cutter  20  configured to reciprocate in the space between jaws  10  (and hence cut tissue disposed between the pair of jaws), and a handle  25  disposed at the proximal end of shaft  15  for carrying a lever  30  for actuating the pair of jaws  10  and a trigger  35  for actuating blade cutter  20 . Endoscopic cutting forceps  5  preferably allow the pair of jaws  10  and blade cutter  20  to be rotated as a unit about the axis of shaft  15  via a knob  40 , and endoscopic cutting forceps  5  preferably allow the pair of jaws  10  to be electrically energized via a button  45  so as to provide electrocautery function to endoscopic cutting forceps  5 . 
     More particularly, and looking now at  FIGS. 1-9 , jaws  10  are each secured to the distal end  50  of a support rod  55 , with support rods  55  and the proximal ends of jaws  10  being disposed within shaft  15 . The proximal ends  60  of support rods  55  are secured to a hub  65 , which is itself secured to a wall  70  of handle  25 . As a result of this construction, jaws  10  are effectively fixed to handle  25 . As seen in the figures, jaws  10  are outwardly biased relative to support rods  55 , so that the distal ends of jaws  10  naturally diverge from one another. Jaws  10  comprise slots  75  ( FIG. 4 ) which receive blade cutter  20 . 
     Shaft  15  is movable relative to handle  25  so as to selectively close down jaws  10 . More particularly, shaft  15  is hollow and is disposed coaxially over the proximal ends of jaws  10  and coaxially over support rods  55 . The proximal end of shaft  15  is connected to a mount  80  ( FIG. 6 ) which is engaged by lever  30  as will hereinafter be discussed. Shaft  15  has a flange  85  intermediate its length. A compression spring  90  is disposed about shaft  15  between a wall  95  of handle  25  and flange  85  of shaft  15  so as to spring-bias shaft  15  in the proximal direction. Another compression spring  100  may be disposed about shaft  15  between flange  85  of shaft  15  and a surface of mount  80  so as to bias mount  80  proximally. 
     As noted above, lever  30  may be used to actuate jaws  10 . More particularly, lever  30  is rotatably pinned at  105  to handle  25  so that when the finger grip  110  of lever  30  is pulled proximally toward palm grip  115  of handle  25 , the opposing end  120  of lever  30  is moved distally, whereby to move mount  80  distally and thereby move shaft  15  distally. Such distal movement of shaft  15  forces jaws  10  to close. When finger grip  110  of lever  30  is released, compression spring  90  returns shaft  15  proximally, whereby to cause jaws  10  to open. Note that blade cutter  20  is received in slots  75  of jaws  10  when jaws  10  are in their open position and blade cutter  20  is also received in slots  75  of jaws  10  when jaws  10  are in their closed position. 
     Looking now at  FIGS. 1-8, 10 and 11 , blade cutter  20  is disposed at the distal end  125  of a drive rod  130 , with the proximal end of blade cutter  20  and drive rod  130  being disposed within shaft  15 . The proximal end of drive rod  130  is secured to a hub  135 . 
     Trigger  35  actuates blade cutter  20 . More particularly, trigger  35  is rotatably pinned at  140  to handle  25  so that when trigger  35  is pulled proximally toward palm grip  115  of handle  25 , the opposing end  145  of trigger  35  is moved distally, whereby to move hub  135  distally and thereby move drive rod  130  and blade cutter  20  distally. Note that when jaws  10  are in their closed position and blade cutter  20  is moved distally, blade cutter  20  will ride distally within slots  75  formed in jaws  10 . 
     As noted above, endoscopic cutting forceps  5  preferably allow the pair of jaws  10  and blade cutter  20  to be rotated as a unit about the axis of shaft  15  via a knob  40 . To this end, knob  40  drivingly engages mount  80  such that when knob  40  is rotated, mount  80  is also rotated, whereby to rotate hub  65  and thereby rotate support rods  55  and hence jaws  10 . Note that inasmuch as blade cutter  20  is received within slots  75  in jaws  10  when jaws  10  are in both their open and closed positions, rotation of jaws  10  will cause blade cutter  20  to rotate in unison with jaws  10 . 
     As also noted above, endoscopic cutting forceps  5  allow the pair of jaws  10  to be electrically energized via a button  45  so as to provide electrocautery function to endoscopic cutting forceps  5 . More particularly, and looking now at  FIGS. 1-3, 5-9 and 12-16 , in the preferred form of the invention, jaws  10  and support rods  55  are formed out of an electrically conductive material, and button  45  is used to activate a switch which connects a power line  150  to jaws  10 . As a result, pressing button  45  electrically energizes jaws  10  so as to provide electrocautery function to endoscopic cutting forceps  5 . In this respect it should be appreciated that, where shaft  15  is made out of an electrically conductive material, and/or where drive rod  130  is made out of an electrically conductive material, an insulating member  155  is disposed between shaft  15  and support rods  55  and jaws  10 , and between drive rod  130  and support rods  55  and jaws  10 , so as to avoid inadvertent short-circuiting of the electrical components of endoscopic cutting forceps  5 . 
     Thus it will be seen that endoscopic cutting forceps  5  generally comprise a pair of jaws  10  disposed at the distal end of a shaft  15 , a blade cutter  20  configured to reciprocate in the space between jaws  10  (and hence cut tissue disposed between the pair of jaws  10 ), and a handle  25  disposed at the proximal end of shaft  15  for carrying a lever  30  for actuating the pair of jaws  10  and a trigger  35  for actuating blade cutter  20 . Endoscopic cutting forceps  5  preferably allow the pair of jaws  10  and blade cutter  20  to be rotated as a unit about the axis of shaft  15  via a knob  40 , and endoscopic cutting forceps  5  preferably allow the pair of jaws  10  to be electrically energized via a button  45  so as to provide electrocautery function to endoscopic cutting forceps  5 . 
     Novel Latching Mechanism 
     In accordance with the present invention, there is also provided a novel latching mechanism for the lever which actuates the jaws, whereby to allow the jaws to be temporarily locked (or clamped) in a closed position about tissue while the blade cutter is actuated to cut the tissue disposed between the clamped jaws. 
     Significantly, the latching mechanism of the present invention is mechanically simple and hence easy and inexpensive to manufacture. 
     In addition, the latching mechanism of the present invention may also be used for the actuating levers of other surgical instruments and/or other lever-actuated devices wherein the latching mechanism is mechanically simple and hence easy and inexpensive to manufacture. 
     Looking next at  FIGS. 1-3, 5-7, 9-11 and 17-26 , there is shown a latching mechanism  200  which comprises one preferred form of the present invention. Latching mechanism  200  generally comprises a selector plate  205  and a latch plate  210 . 
     Selector plate  205  serves to selectively position latch plate  210  within handle  25 . Selector plate  205  is movably mounted to handle  25 , and latch plate  210  is mounted to selector plate  205 , such that, by adjusting the position of support plate  205  within handle  25 , the position of latch plate  210  may also be adjusted within handle  25 . In this way selector plate  205  can be used to selectively position latch plate  210  in a “latch operative position” or in a “latch inoperative position” within handle  25 , as will hereinafter be discussed. 
     More particularly, selector plate  205  is slidably mounted to handle  25  of endoscopic cutting forceps  5 . A thumb button  215  protrudes through a window  220  formed in handle  25  so that the user can adjustably position selector plate  205  (and hence adjustably position latch plate  210 ) within handle  25 . Detents  225  are formed in selector plate  205  and cooperate with a protrusion  230  formed on handle  25  whereby to allow selector plate  225  to be maintained in a “latch operative position” or in a “latch inoperative position” within handle  25  until urged otherwise by the user. 
     Latch plate  210  is slidably mounted to selector plate  205 . More particularly, latch plate  210  comprises a body  235  having a loop spring  240  extending therefrom ( FIG. 24 ). In one preferred form of the invention, loop spring  240  is formed integral with body  235 . Loop spring  240  comprises a bore  245  which is mounted on a pin  250  of selector plate  205 . Loop spring  240  biases body  235  of latch plate  210  into a given position on selector plate  205 , but permits body  235  of latch plate  210  to be slidably moved on selector plate  205  (both towards and away from pin  250  on selector plate  205 ) against the power of loop spring  240 . In one preferred form of the invention, latch plate  210  moves linearly with respect to handle  25  as latch plate  210  moves on selector plate  205 . Body  235  of latch plate  210  includes a flange  257  which is slidably mounted on selector plate  205 , whereby to stabilize latch plate  210  as it moves on selector plate  205 . As a result of this construction, body  235  of latch plate  210  can be urged away from pin  250  of selector plate  205  against the power of loop spring  240 , or body  235  of latch plate  210  can be urged toward pin  250  of selector plate  205  against the power of loop spring  240 . 
     A latch element  255  is mounted to body  235  of latch plate  210 . In one preferred form of the invention, latch element  255  is formed integral with body  235  of latch plate  210 . Latch element  255  comprises a first surface  260 , a second surface  265 , and a third surface  270  ( FIG. 26 ). In one preferred form of the invention, first surface  260  comprises a substantially linear configuration, second surface  265  comprises a concave configuration, and third surface  270  comprises a slightly convex or substantially linear configuration. 
     First surface  260 , second surface  265  and third surface  270  together define a labyrinth (i.e., a non-linear track comprising a leading first surface  260 , a concave second surface  265 , and a trailing third surface  270 , whereby to form a tortuous path with a concavity intermediate its length), and interact with a latch pin  275  ( FIG. 26 ) formed on lever  30 , so as to provide the desired latching function. 
     More particularly, when selector plate  205  is appropriately positioned within handle  25  so that the apparatus is configured in the “latch operative position”, and when lever  30  is thereafter pulled toward palm grip  115  of handle  25  (i.e., so as to close jaws  10 ), latch pin  275  engages first surface  260  of latch element  255  and forces latch plate  210  away from pin  250 , against the power of loop spring  240 . Latch pin  275  rides along first surface  260  of latch element  255  until latch pin  275  reaches the end of first surface  260 , whereupon latch pin  275  moves onto second surface  265  of latch element  255 . As soon as latch pin  275  moves onto the concave second surface  265 , loop spring  240  pulls body  235  of latch plate  210  back toward pin  250 , until latch pin  275  seats at the base of concave second surface  265 . At this point, lever  30  will be maintained in this position (i.e., the “latched” position, with jaws  10  clamped) until lever  30  is thereafter pulled again. More particularly, when it is thereafter desired to unclamp jaws  10 , lever  30  is pulled again, against the power of loop spring  240 , so as to cause latch pin  275  to move out of the base of concave second surface  265  of latch element  255  and further along concave second surface  265 . As soon as latch pin  275  clears the end of concave second surface  265  and moves onto third surface  270  of latch element  255 , loop spring  240  pulls latch plate  210  back toward pin  250 , until latch pin  275  is returned to its original starting position clear of third surface  270 . At this point, lever  30  will have been returned to its original starting position, pending a further cycling of endoscopic cutting forceps  5 . 
     It will be appreciated that the latching function just described relies upon the interaction of latch pin  275  with latch element  255 . It will also be appreciated that selector plate  205  allows the position of latch plate  210  to be adjusted within handle  25 . Thus selector plate  205  provides the ability to render the latching function operative or inoperative by adjusting the position of latch plate  210  (and hence the position of latch element  255 ) vis-à-vis the position of lever  30  (and hence the orbit of latch pin  275 ). More particularly, by positioning selector plate  205  so that the position of latch element  255  is outside the orbit of latch pin  275 , the selector plate can be used to put the apparatus in a “latch inoperative position”. Conversely, by positioning selector plate  205  so that the position of latch element  255  is within the orbit of latch pin  275 , the selector plate can be used to put the apparatus in a “latch operative position”. The user adjusts the position of selector plate  205  using thumb button  215 . 
     Exemplary Operation of the Novel Latching Mechanism of the Endoscopic Cutting Forceps 
       FIGS. 27-38  illustrate operation of the endoscopic cutting forceps  5  (note that the specific constructions shown in  FIGS. 27-38  may differ slightly from the specific constructions shown in  FIGS. 1-26 , however,  FIGS. 27-38  depict a common operation of the latching function of the present invention). More particularly,  FIGS. 27-35  show endoscopic cutting forceps  5  with selector plate  205  set in the “latch operative position” and with the apparatus cycling through a complete latching/unlatching operation.  FIGS. 36-38  show endoscopic cutting forceps  5  with selector plate  205  set in the “latch inoperative position” and with lever  30  cycling through a complete “pull and release” operation. 
     Alternative Preferred Embodiments 
     In the preceding description, lever  30  is described as being rotatably pinned to handle  25  at  105 . However, it should be appreciated that other connections may also be employed. By way of example but not limitation, lever  30  may be movably mounted to handle  25  by the legs of a so-called “4-bar” mechanism. 
     It should be appreciated that, if desired, selector plate  205  may move in a direction which is different than the direction of movement of latch plate  210 , provided, however, that movement of selector plate  205  moves latch plate  210  into, and out of, the orbit of latch pin  275 . By way of example but not limitation, selector plate  205  could move in a direction perpendicular to the direction of movement of latch plate  210 , whereby to move latch plate  210  into, and out of, the orbit of latch pin  275 . 
     If desired, latch plate  210  may be movably mounted to selector plate  205  by a variety of means, so as to provide a variety of different movements, e.g., linear movement, pivoting movement, prescribed motion such as by a so-called “4-bar” mechanism, traversing in an arcuate track, etc. 
     Thus it will be seen that the present invention provides a new and improved latching mechanism for an endoscopic cutting forceps wherein the latching mechanism is mechanically simple and hence easy and inexpensive to manufacture. 
     It will also be appreciated that the new and improved latching mechanism of the present invention may be used in conjunction with the actuating levers of other surgical instruments and/or other lever-actuated devices, whereby to provide a latching mechanism which is mechanically simple and hence easy and inexpensive to manufacture. 
     Modifications of the Preferred Embodiments 
     It will be appreciated that various modifications may be made to the preferred embodiments discussed above without departing from the scope of the present invention. 
     Thus, for example, the locations of selector plate  205 /latch plate  210  and latch pin  275  may be reversed, i.e., selector plate  205  and latch plate  210  may be mounted on lever  30  and latch pin  275  may be mounted on handle  25 . 
     By way of further example but not limitation, selector plate  205  may be omitted, in which case latch plate  210  is slidably mounted directly to handle  25  (or, if the location of latch plate  210  and latch pin  275  are reversed, slidably mounted directly to lever  30 ). Of course, in this form of the invention, the apparatus is always set in the “latch operative position” and is incapable of being set in the “latch inoperative position”. 
     It should be understood that many additional changes in the details, materials, steps and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the present invention, may be made by those skilled in the art while still remaining within the principles and scope of the invention.