Abstract:
A driver unit of a vertically slidable type is constructed by mounting a staple cartridge to a cartridge holder so as to freely slide in a vertical direction, and by urging the staple cartridge toward a clincher unit opposed thereto by a spring. When a clincher sleeve has descended to push the staple cartridge, the staple cartridge will move up and down in parallel, and accordingly, a relative angle of a clincher to a driver plate will not change.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an electric stapler, and more particularly, to an electric stapler in which a clincher and a driver are separated from each other and arranged in a vertical direction.  
           [0003]    2. Description of the Related Art  
           [0004]    [0004]FIG. 4 shows an electric stapler adapted to be incorporated mainly in a copying machine. A clincher unit  1  and a driver unit  2  are vertically separated from each other in order to bind a document at its center portion. The clincher unit  1  is fixed to an upper base plate  3 , and the driver unit  2  is fixed to a lower base plate  4  which is arranged in parallel to the upper base plate  3  spaced therefrom.  
           [0005]    Into a clincher guide  5  formed in a vertical direction in a front part (a left side in the drawing) of the clincher unit  1 , a clincher sleeve  6  and a clincher  7  are inserted. The clincher sleeve  6  and the clincher  7  are driven to move up and down by means of a motor  8 , a reduction gear train  9 , cam levers  10  at left and right sides (in a direction of Z axis in the drawing), and a central cam lever  11 .  
           [0006]    When the motor  8  is energized, the cam levers  10  at the left and right sides, which are engaged with an eccentric roller  12  attached to a final reduction gear  9   a , move upward and downward about a shaft  13  as a pivotal axis. The clincher sleeve  6  and the clincher  7 , which are engaged in elongated holes in front parts of the cam levers  10 , perform one cycle of a reciprocating motion in which they move upward to return to the standby position after they have moved downward from a standby position. On this occasion, after the clincher sleeve  6  has come into contact with sheets of paper to discontinue the downward movement, the central cam lever  11  further pushes down the clincher  7 , and the clincher  7  bends legs of the staple which has entered in the clincher sleeve  6 , into a flat shape.  
           [0007]    The driver unit  2  is so designed that its front part freely moves up and down within a determined range about a shaft  14  in its rear part as a pivotal axis, and is urged to an elevated position by means of a compression spring  15 . Into a driver guide  16  in the front part of the driver unit  2 , a driver plate  17  and a forming plate  18  are inserted in an overlapped manner. A lower end of the driver plate  17  is in contact with a stopper  19  provided on a frame of the stapler. Numeral  20  designates a staple cartridge. A staple sheet S to which a number of straight staples are bonded in parallel is loaded in the staple cartridge  20 .  
           [0008]    [0008]FIG. 5 shows the electric stapler in operation. When the clincher sleeve  6  and the clincher  7  move downward to push down the front part of the driver unit  2 , other parts than the driver plate  17  and the forming plate  18  which are in contact with the stopper  19  rotate downward. With this rotation, the driver plate  17  is projected upward from the driver unit  2 . A staple in a foremost row inside the driver guide  16  is pushed upward and clamped by means of the clincher sleeve  6  and the clincher  7  to pass through the document (not shown), and both left and right legs of the staple are bent inwardly by means of the clincher  7 . At the same time, a staple in the next row of the ejected staple is formed by the forming plate  18  into a bent shape like a gate.  
           [0009]    As described above, the conventional electric stapler has such a structure that the clincher sleeve  6  slides downward rectilinearly to push the driver unit  2 , and the driver unit  2  rotates downwardly about the shaft  14  as the pivotal axis. Accordingly, when the document has been clamped between the clincher sleeve  6  and the driver unit  2 , an angle of the driver plate  17  and an ejection angle of the staple may change according to thickness of the document. For this reason, the clincher sleeve  6  must be accurately aligned with the driver plate  17  so as to follow a change of the angle of the driver plate  17 . Even a minor error in the alignment may result in distortion or clogging of the staples, and there has been a problem that high accuracy is required with respect to precision of the components and assembling work, and assembling adjustment is also difficult.  
           [0010]    Therefore, there has arisen a technical problem to be solved for stabilizing the stapling that the clincher and the driver plate must be arranged so as to face with each other at a constant angle regardless of thickness of the document to be bound. An object of the present invention is to solve the above described problem.  
         SUMMARY OF THE INVENTION  
         [0011]    This invention has been made in order to attain the above described object and to provide a electric stapler for binding a document inserted between a driver unit and a clincher unit, the electric stapler comprising the driver unit including a driver plate adapted to eject staples and a staple cartridge, and the clincher unit including a clincher adapted to bend legs of each of the staples which have been ejected and a clincher driving mechanism, wherein the driver unit and the clincher unit are separated from each other and arranged in a vertical direction. The electric stapler is characterized in that the driver unit is composed of a cartridge holder fixed to a frame of the electric stapler, said staple cartridge mounted to the cartridge holder so as to freely slide up and down, a spring for urging the staple cartridge toward the clincher unit opposed thereto, and the driver plate incorporated in the cartridge holder, the clincher of the clincher unit being so constructed as to push the staple cartridge to slide, whereby the staples in the staple cartridge are ejected by means of a driver in the cartridge holder. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    [0012]FIG. 1 is an explanatory view in a longitudinal section of a electric stapler in one embodiment according to the invention.  
         [0013]    [0013]FIG. 2 is an explanatory view in a longitudinal section of a feeding claw mechanism in a driver unit as shown in FIG. 1.  
         [0014]    [0014]FIG. 3 is an explanatory view in a longitudinal section of the electric stapler in operation.  
         [0015]    [0015]FIG. 4 is an explanatory view in a longitudinal section of a electric stapler in a conventional example.  
         [0016]    [0016]FIG. 5 is an explanatory view in a longitudinal section of the electric stapler in operation in the conventional example. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0017]    An embodiment according to the invention will be described in detail referring to the drawings. FIG. 1 shows an electric stapler, in which a clincher unit  1  and a driver unit  21  are separated vertically. The clincher unit  1  is fixed to an upper base plate  3 , and the driver unit  2  is fixed to a lower base plate  4 . Because the clincher unit  1  has the same structure as in the conventional electric stapler as shown in FIG. 4, the clincher unit  1  will not be further described, but the driver unit  21  only will be described here.  
         [0018]    The driver unit  21  comprises a cartridge holder  22  fixed to a frame (not shown) of the electric stapler and a staple cartridge  23  mounted to the cartridge holder  22 . The staple cartridge  23  is engaged with guide grooves  24  formed in a vertical direction on an inner wall face of the cartridge holder  22  at left and right sides thereof (in a direction of Z axis in the drawing). The staple cartridge  23  is held by the cartridge holder  22  in such a manner that it can slide up and down.  
         [0019]    The staple cartridge  23  is provided with a driver guide  25  in a vertical direction in a front part thereof (a left side in the drawing). Into the driver guide  25 , there are inserted a driver plate  26  and a forming plate  27 .  
         [0020]    A lower end of the driver plate  26  is bent in an L-shape. A compression spring  29  inserted between the L-shaped bent portion and a staple guide  28  in an upper part urges the staple cartridge  23  upward. A pressure plate  31  is provided on a bottom inside the staple cartridge  23  interposing a compression spring  30 , and a staple sheet S piled on the pressure plate  31  is pressed to a ceiling face of the staple guide  28 .  
         [0021]    There is provided a feeding claw unit  32  on the staple guide  28  so as to freely slide back and forth. FIG. 2 shows the feeding claw unit  32  which includes a slide plate  33 , a feeding claw  34  provided on a lower face of the slide plate  33  and directed diagonally downward in a forward direction, and a shaft  35  provided in a rear part of the slide plate  33  and loaded with a compression spring, so that the feeding claw unit  32  is urged forward in the staple cartridge  23 .  
         [0022]    At both left and right sides of a front part of the slide plate  33 , there are formed cams  37  which are oriented downward. The cams  37  are respectively engaged with backwardly slanted cam grooves  38  which are formed on left and right inner wall faces of the cartridge holder  22 . Accordingly, when the staple cartridge  23  has moved downward with respect to the fixed cartridge holder  22 , the feeding claw unit  32  retreats along slanted faces of the cam grooves  38 , and the feeding claw  34  slides along a surface of the staple sheet S. On the contrary, when the staple cartridge  23  has moved upward, the feeding claw unit  32  is pressed by means of the compression spring  36  and moves forward. On this occasion, the feeding claw  34  is brought into engagement with a groove between the staples of the staple sheet S to feed the staple sheet S in a forward direction.  
         [0023]    It is also advantageous that because there is no shaft for supporting the driver unit in the rear part of the staple cartridge (a right side in the drawing), different from the conventional driver unit, the staple sheet S can be loaded into the staple cartridge from the back, and operability will be enhanced.  
         [0024]    Then, operation of the electric stapler will be described. When a document D has been fed between the clincher unit  1  and the driver unit  21  in a standby state as shown in FIG. 1, the motor  8  of the clincher unit  1  is energized by a document detecting signal from a sensor which is not shown. Then, the clincher sleeve  6  and the clincher  7  integrally descend as described in the conventional example, and press the document D onto an upper face of the staple cartridge  23  to push the document D and the staple cartridge  23  downward.  
         [0025]    At this moment, the driver plate  26  and the forming plate  27  will not descend because they are in contact with the bottom face of the cartridge holder  22  at their lower ends, but the staple cartridge  23  will descend as shown in FIG. 3. Accordingly, the driver plate  26  is projected upward from the driver guide  25 . With this motion, the staple in the staple guide  28  will be ejected by the driver plate  26  and the legs of the staple which have passed through the document D will be pressed into the clincher sleeve  6 .  
         [0026]    Although not shown in the drawings, an opening of the clincher sleeve  6  at its lower end is in a diverged trapezoidal shape in a sectional view as seen from a front face, by which the legs of the staple which have been pressed in the opening of the clincher sleeve  6  can be bent inwardly. Then, the central cam lever  11  of the clincher unit  1  further pushes down the clincher  7  thereby to bend the legs of the staple, which have been pushed into the clincher sleeve  6 , into a flat shape.  
         [0027]    Simultaneously with the above described stapling motion, the leading staple in the driver guide of the driver unit  21  will be bent at both left and right sides thereof at the right angle by means of the forming plate  27  to be formed into a shape like a gate.  
         [0028]    Thereafter, the clincher sleeve  6  and the clincher  7  proceed into an ascending stroke and are returned to the standby position as shown in FIG. 1. The driver unit  21  released from the pressure will also ascend to the standby position, while the driver plate  26  and the forming plate  27  will descend relatively, and the leading staple will be supplied into the driver guide  25  by means of the feeding claw  34 .  
         [0029]    It is apparent that the invention is not limited to the above described embodiment, but various modifications can be made in a technical scope of this invention, and that the invention also covers those which have been modified.  
         [0030]    As described herein above, the electric stapler according to the invention has such a structure that the staple cartridge of the driver unit moves up and down in parallel with respect to the standby position to eject the staple by means of the driver plate in the cartridge holder. Therefore, different from the conventional driver unit which is adapted to rotate up and down about the shaft as the pivotal axis, the relative angle of the clincher to the driver plate will not change. Thus, the stapling will be stabilized and a fear of an accident such as distortion or clogging of the staples can be avoided.