Abstract:
An electric stapler for binding a material with a staple comprising a driver, a cutter, and a clincher. The driver engages the staple and drives leg portions of the staple through the material to be bound. The cutter cuts the leg portions of the staple in a predetermined length and forms a cut surface in each of the leg portions. The cut surface forms an obtuse angle where the cut surface and an outer surface of the leg portions meet each other. The clincher bends the leg portions of the staple after the leg portions piercing the material to be bound are cut.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an electric stapler. More specifically, the present invention relates to a cutting mechanism for an electric stapler in which unnecessary portions of the leg portions of a staple, which pass through and are projected from an object to be stapled, are cut after the leg portions are bent inward. 
     2. Description of the Related Art 
     To staple a large number of sheets (for example, 100 sheets), a staple of which the crown portion is wide and the leg portions are long is generally used. When a small number of sheets are stapled with the same type of staple and the leg portions of the staple are bent, the leg portions are overlapped each other. In order to prevent the leg portions from being overlapped, a mechanism is known in which leg portions of a stapler are clinched after necessary portions of the leg portions for stapling, which pass through and are projected from the reverse side of a stapled object, are left and the rest of the leg portions are cut away. The above cutting mechanism, as shown in FIGS. 12A and 12B, includes a couple of support plates  30  for rotatably supporting movable clinchers (not shown). A cutter  31  is disposed at an intermediate portion of the couple of support plate  30  in a state that it is movable in the direction at a right angle with the support plates. The cutter  31  includes an opening  33  allowing the leg portions  32  of a staple to pass therethrough. The leg portions  32  of the staple, after they pass through a stapled object  34 , are inserted into the space between the support plates  30 , and pass through the opening  33 . In this state, the cutter  31  is moved to cut away unnecessary portions of the leg portions  32  of the staple, as shown in FIG.  12 C. 
     However, in the conventional cutting mechanism, when the leg portions of the staple are cut as described above, the corners  35  of the leg portions are formed at a substantially right angle. Therefore, as shown in FIG. 12D, when the stapling work ends and a stapled booklet is, for example, laid on top of another, there is a danger that the corners  35  of the leg portions of one booklet scratch the surface of the paper of another laid booklet  34   a.    
     Accordingly, an object of the present invention is to provide a cutting mechanism for leg portions of staples in use with an electric stapler which is free from the above problem that the leg portions of a staple scratch or break the surface of another stapled object. 
     SUMMARY OF THE INVENTION 
     In order to attain the above object, the present invention provides an electric stapler for binding a material with a staple comprising a driver, a cutter, and a clincher. The driver engages the staple and drives leg portions of the staple through the material to be bound. The cutter cuts the leg portions of the staple in a predetermined length and forms a cut surface in each of the leg portions. The cut surface forms an obtuse angle where the cut surface and an outer surface of the leg portions meet each other. The clincher bends the leg portions of the staple after the leg portions piercing the material to be bound are cut. 
     Further, it is preferable that curved plates are disposed under the cutter, and the leg portions of the staple are bent inward by the curved plates, and then the leg portions are cut. 
     Moreover, it is more preferable that the leg portions of the staple are cut with a U-shaped or V-shaped cutter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing a main portion of an electric stapler; 
     FIG. 2 is a sectional view showing a stapling portion of the electric stapler; 
     FIG. 3 is an exploded perspective view showing a cutting mechanism for staple legs and a clincher mechanism in the electric stapler according to the present invention; 
     FIG. 4 is an exploded perspective view showing a main portion of the cutting mechanism for staple legs; 
     FIG. 5 is a traverse sectional view showing the cutting mechanism for staple legs; 
     FIGS. 6A and 6B are diagrams explaining the operation of the clincher mechanism; 
     FIG. 7 is a cross sectional view showing a state that the leg portions of a staple are put in the cutting mechanism for staple legs; 
     FIG. 8 is a perspective view showing a main potion of the electric stapler when the cutting mechanism for staple legs is operated; 
     FIGS. 9A and 9B are diagrams explaining an operation of the cutting mechanism for staple legs; 
     FIG. 10A is a diagram showing the cutting of the leg portions of a staple; 
     FIG. 10B is a diagram showing the bending of the leg portions after cutting. 
     FIGS. 11A and 11B are diagrams showing explaining an operation with other types of the cutter; 
     FIG. 12A is a cross sectional view of a conventional cutting mechanism when the cutting mechanism is viewed from the front; 
     FIG. 12B is a cross sectional view of the conventional cutting mechanism as shown in FIG. 12A when it is viewed from the side; 
     FIG. 12C is a diagram explaining an operation of the conventional cutting mechanism as shown in FIG. 12A; and 
     FIG. 12D is a diagram showing a stapled state according to the conventional cutting mechanism as shown in FIG.  12 A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, preferred embodiments of a vehicle headlight will be described in detail with reference to the attached drawings. However, the preferred embodiments are merely an example of the present invention, and thus, the specific features described below are merely used to more easily describe such embodiments and to provide an overall understanding of the present invention. Accordingly, one skilled in the art will readily recognize that the present invention is not limited to the specific embodiment described below. Furthermore, the description of various configurations of the present invention which would have been known to one skilled in the art are omitted for the sake of clarity and brevity. 
     FIG. 1 is a perspective view showing a main portion of an electric stapler. As shown, the electric stapler includes a driving mechanism for a driver, a cutting mechanism, and a clincher mechanism. Both the cutting mechanism for a driver and the clincher mechanism are disposed under the driver mechanism. 
     The driver mechanism for a driver includes grooved cams  1  driven by an electric motor (not shown), drive links  2  which are swung as the grooved cams  1  are turned, a driver holder  4  supported by a coupling bar  3 , which couples both leading ends of the drive links  2 , and a driver  5  supported by the driver holder  4 . In the thus constructed driver mechanism, when the grooved cams  1  are turned by the electric motor, the drive links  2  is swung and the driver  5  is vertically moved. 
     A staple supplying device (not shown) for supplying staples is provided under the driver  5 . A stapling table  7  on which a stapled object  15  is located is provided under the driver  5 . A couple of clincher holders  8 , while being spaced from each other, are located under the stapling table  7 . The clincher holders  8  guide the leg portions  6   a  of a staple  6  which is driven out by the driver  5 , while the clincher holders  8  holds a movable clincher to be described later. A cutting mechanism for staple legs is penetrating the clincher holders  8  and a clincher mechanism are disposed in the clincher holders  8 . 
     As shown in FIGS. 2 and 3, the cutting mechanism for staple legs includes a rectangular hole  9  laterally elongated in the clincher holder  8 . In the rectangular hole  9 , a block-shaped cutter  10  is mounted and movable into and out of the rectangular hole  9 . Leg receiving holes  11  are formed in the front portion of the cutter  10  so as to receive leg portions  6   a  of the staple  6 . The leg receiving holes  11  are formed in a vertical direction and with elongated laterally. 
     As shown in FIGS. 4 and 5, curved plates  14  are disposed under the cutter. 
     As shown in FIGS. 2 and 3, the stapling table  7  includes an opening  12  defined by a couple of the clincher holders  8 . The opening  12  is positioned where a staple  6  reaches when the driver  5  is downwardly driven and hits the staple  6 . The leg portions  6   a  of the staple  6  pass a space defined between a couple of the clincher holders  8 . As shown in FIGS. 2,  3  and  6 A, a couple of movable clinchers  13  are rotatably arranged between the clincher holders  8 . Each of movable clinchers  13  is arcuately curved so as to avoid the rectangular hole  9  of the clincher holders  8 . The bases  13   a  of the movable clinchers  13  are overlapped each other and rotatably supported by a shaft  26 . When the movable clinchers  13  are turned, each leading end  13   b  is moved along the underside of the stapled object  15 , and the movable clinchers  13  are opened and closed. Each of the movable clinchers  13  includes an engaging groove  16  which is formed in the outer edge at a lower position thereof. 
     As shown in FIGS. 1,  3  and  6 A, clincher levers  17  are respectively arranged under the movable clinchers  13 , and are vertically movable. The clincher levers  17  are arranged in such a manner that the leading ends of the clincher levers  17  are engageable with engaging grooves  16  of the movable clincher  13 . The clincher levers  17  are swingably supported at their central portion by a support shaft  19 . The support shaft  19  is provided on a base table  18  integral with the stapling table  7  of the electric stapler. A drive link  20  is coupled with the rear portion of each of the clincher levers  17 . Each rear end of the drive links  20  is engaged with a groove (not shown) formed on the rear side of the grooved cam  1 . A triangular link plate  21  is located near each of clincher levers  17  and supported by a shaft  22  in a swingable fashion. The front end of the triangular link plate  21  is coupled with the corresponding clincher lever  17  by a shaft  26 , and the upper end part thereof is coupled with the cutter  10  by a shaft  23 . With the above arrangement, when the grooved cams  1  are turned, the drive links  20  is swung, and then the movable clinchers  13  and the cutter  10  is operated. 
     In the electric stapler thus constructed, when the grooved cams  1  are turned by the electric motor, the drive links  2  is swung and then the driver  5  is vertically moved. When the driver  5  is downwardly driven, it hits the staple  6 , and the leg portions  6   a  of the staple  6  pierce through the stapled object  15 . The leg portions  6   a  of the staple  6 , which have passed through the stapled object  15 , are respectively inserted into the leg receiving holes  11  of the cutter  10 , which is projected and located in front of the clincher holders. At this time, tips of the leg portions  6   a  abut against the curved plates  14  located thereunder, and the leg portions  6   a  are bent inward. 
     Thereafter, the drive link  20  is similarly turned by the grooved cams  1  to move the clincher levers  17  upwardly. Thus, as shown in FIG. 8, the link plates  21  are turned to retract the cutter  10 , which has been located in front of the clincher holders. Then, the cutter  10  cuts the unnecessary portions  25  of the leg portions  6   a,  as shown in FIGS.  9 ( a ) and  9 ( b ). 
     Immediately after cutting the leg portions of the staplers, the front ends of the clincher levers  17  engage with the engaging grooves  16  of the movable clinchers  13  to push the movable clinchers  13  upwardly. As a result, the movable clinchers  13  turn in the closing direction about the shaft  26 , to thereby bend the leg portions  6   a  of the staple  6  inward, as shown in FIGS. 6A and 6B. Then the stapling operation of the electric stapler ends. 
     As described above, after the leg portions  6   a  of staple pass through the stapled object  15 , the unnecessary portions  25  of the leg portions  6   a  abut against the curved plates  14  to be curled inward. Then, after the leg portions  6   a  are curled inward, the unnecessary portions  25  are cut away by the cutter  10 . Therefore, an angle of an outer surface “a” of each leg portion  6   a  with respect to a cut surface “b” is obtuse as in FIG.  10 A. Where the angle is obtuse, the cut surface is hard to be burred, and hence burr is little formed at the outside of the cut portion of each leg portion. Even if burr is formed, it is negligible in size. For this reason, when the movable clinchers  13  bend the leg portions  6   a  of the staple, no or a little burr is exposed outside as shown in FIG.  10 B. Therefore, when the stapling work ends and the stapled booklets are overlapped on top of another, there is no danger that the corners of the leg portions of one booklet scratch the surface of the paper of another booklet. 
     It is evident that the shape of the cutter for cutting the leg portions  6   a  is not limited to the planar shape as mentioned above. It may be V shaped as shown in FIG. 11A or U shaped as shown in FIG.  11 B. 
     While only certain embodiments of the present invention have been specifically described herein, it will be apparent that numerous modifications may be made thereto without departing from the spirit and scope of the invention. 
     The present invention is based on Japanese Patent Application No. Hei. 10-297005 which is incorporated herein by reference.