Abstract:
An electrically powered stapler has inner side walls incorporating a staple carrier for feeding a cartridge of staplers towards a stapling station where one of the staples in the cartridge is positioned for being driven by an electric motor through a number of sheets held in the station. The stapler includes a staple carrier-release button for mechanically releasing the staple carrier from an in-use stapling position (for the purpose of refilling the staple carrier with a staple cartridge). An electrical disable switch is associated is with the staple carrier to disable the motor if the staple carrier is not in the in-use stapling position.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The invention relates to staplers and particularly to power staplers that do not require manual operation.  
           [0002]    Staplers are commonly used in offices and homes for stapling together sheets of paper, but may be used for stapling together other items such as textile pieces and the like. In each case the ‘sheets’ are placed on an anvil and a stapler is pressed closed. This typically presses out a staple from a remote end of a cartridge of staples and through the sheets on the anvil, and closes the staple to attach the sheets together. Such staplers are often manually operated.  
           [0003]    Electrically powered staplers have been proposed in U.S. Pat. Nos. 6,068,173 and 5,222,645. These patents essentially show the mechanism of a manual stapler construction that is mechanised by using force generated by an electric battery-operated motor mounted inside the stapler. Thus, mechanical limitations associated with manual staplers are not overcome although such ‘power staplers’ provide some inherent improvements and convenience by making the stapling operation at least semi-automatic.  
           [0004]    An improved electrical stapler is disclosed in the present applicant&#39;s co-pending European patent application number 01305752.6. It would be desirable to improve the functionality of the stapler disclosed in that application by providing a special switching set-up to prevent actuation of the stapler when the staple carrier is not fully home in the use-position.  
         OBJECTS OF THE INVENTION  
         [0005]    It is an object of the invention provide a powered stapler that overcomes or at least reduces these problems and/or provides improved functionality.  
         SUMMARY OF THE INVENTION  
         [0006]    There is disclosed herein an electrically powered stapler having a inner side walls incorporating a stapler carrier for feeding a cartridge of staples towards a stapling station where one of the staples in the cartridge is positioned for being driven by an electric motor through a number of sheets held in the station above a horizontal anvil, the stapler including a staple carrier-release button for mechanically releasing the staple carrier from an in-use stapling position (for the purpose of refilling the staple carrier with a staple cartridge), the stapler further comprising an electrical disable switch associated with the staple carrier to disable the motor if the staple carrier is not in the in-use stapling position.  
           [0007]    Preferably, a staple trigger-switch is provided near the anvil to close a circuit to the electric motor.  
           [0008]    Preferably the disable-switch is in circuit with the trigger-switch.  
           [0009]    Preferably the staple carrier-release button has associated with it a mechanism pressing against a back end of the staple carrier.  
           [0010]    Preferably the staple carrier is mounted pivotally to the housing.  
           [0011]    Typically, a punch plate is supported for sliding movement above the anvil in substantially perpendicular relationship to the anvil.  
           [0012]    Typically, an elongate intermediately pivoted lever having one end arranged to press down and lift up the punch plate to carry out stapling operations.  
           [0013]    Typically, a gear has a crank that pushes the lever to move the other end of the lever up and down as the gear rotates.  
           [0014]    Preferably, the electric motor is coupled to intermittently drive the gear through single revolution or some other predefined angular movement for each stapling operation.  
           [0015]    The lever preferably has an elongate closed channel to receive the crank such that the crank can slide backwards and forwards along the channel as the gear rotates to move the lever up and down during each stapling operation.  
           [0016]    The channel is preferably non-uniformly or asymmetrically disposed about the longitudinal axis of the elongated lever such that the cutting blade is moved up and down at different linear motion rates relative to a constant rotational speed of the gear.  
           [0017]    A staple extractor tool may be provided that is mounted for sliding movement to a base of the housing and is arranged to be manually moved and exposed at one end of the housing when required for use.  
           [0018]    In some forms of the invention the apparatus is battery powered. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0019]    A preferred from of the invention will now be described with reference to the accompanying drawings, in which:  
         [0020]    [0020]FIG. 1 is an exploded isometric view of a stapler;  
         [0021]    [0021]FIG. 2 is an interior isometric view of the mechanism of the stapler of FIG. 1;  
         [0022]    [0022]FIG. 3 is a side elevational view of the mechanism shown in FIG. 2;  
         [0023]    [0023]FIG. 4 is a diagrammatic side view of mechanical components of the stapler showing the lever and punch plate in a first position;  
         [0024]    [0024]FIG. 5 is a diagrammatic side view of the basic components of the stapler showing the lever and punch plate in a second position; and  
         [0025]    [0025]FIG. 6 is an isometric view of a stapling adjustment carriage of the stapler;  
         [0026]    [0026]FIG. 7 is a plan view of the carriage of FIG. 6;  
         [0027]    [0027]FIG. 8 is a side view of the carriage of FIG. 6;  
         [0028]    [0028]FIGS. 9, 10,  11  and  12  are side views of the staple carrier and release switch in different positions, and  
         [0029]    [0029]FIG. 13 is a schematic elevational view of internal components of the stapler. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0030]    Referring to the Figures, there is shown a power stapler having an outer housing  10  which defines a slot  11  for receiving edges of sheets of paper (not shown) to be stapled together. The power stapler B includes a stapling station having a horizontal anvil  12  and elongated staple carrier  13  for holding a staple cartridge. The staple carrier  13  is mounted for sliding axial movement out of the housing  10  when it is necessary to replace the staple cartridge. A removable battery compartment cover  14  provides access to replace batteries in the compartment that extends within the base of the housing  10 . A recharging/power socket  20  is provided to power the stapler and/or recharge its batteries. A staple removal tool  15  is mounted for sliding movement in or under the base  10  and is mounted to allow manual movement from a position on or under the base  10  to an extended position, as shown in FIG. 1 when required for use.  
         [0031]    There are two moulded inner side-walls  16  and  17  that fit into the housing  10  for supporting and containing components of the stapler described below. A punch blade or punch plate  18  is carried by a support  19 . The punch blade  18  with the support  19  is arranged to slide vertically The support  19  has a central aperture  21  for receiving an end of an elongate arm  22  that is best seen in FIG. 2. The arm  22  is mounted between each side-wall  16 ,  17  at position  30  as shown in FIG. 2. Arm  22  serves as a mounting frame for the gears.  
         [0032]    At each side of the arm  22  there is a lever  31 . Each lever  31  has a pivot axle  23  and an elongated closed channel  24  for receiving a crank pin  25 . The crank pin is mounted on the side of a gear  26 , which is rotatable in a vertical plane. Intermediate gears  27 ,  28  and  32  connect the gear  26  to an electric drive motor  29 .  
         [0033]    FIGS.  2  to  5  also show the staple carrier  13  and a spring  31  for biasing staples (not shown) in the staple carrier  13  towards the stapling station. The staple carrier  13  is mounted pivotally at  33  between the sidewalls.  
         [0034]    In general, the well-known stapling operation comprises pressing one staple in the staple carrier  13  downwardly through sheets of paper placed in the stapling station (i.e. in the slot  11 ) and against the anvil  12  to close the staple. Commonly, stapling operations are performed manually but in the preferred embodiment of the invention, stapling operations are carried out by using a contact spring electric switch  34  to turn ON the motor  29  to rotate the gear  26  one complete revolution. The switch is automatically operated when the sheets are pushed fully into the slot  11 . The switch  34  is mounted on an adjustment carriage  35  that is movable by pushing tab  36  so as to set how far min from the edge of the sheets the staple is to be inserted. The adjustment carriage provides a buffer surface  37  against which the edges of the paper bear to define this offset.  
         [0035]    [0035]FIGS. 3, 4 and  5  show three sequential positions of the punch blade  18 . In FIG. 3, the stapler is “at rest” with the punch blade  18  at its highest position. When sheets of paper are placed fully into the slot  11 , the motor  29  is momentarily turned on and off to cause the gear  26  to rotate 360 degrees. The staple carrier  13  moves to its lowest position first due to its interaction with a coil spring  38  as shown in FIG. 5. FIGS. 3, 4 and  5  illustrate the respective positions of the levers  31  and the support  19  throughout approximately the first 175 degrees of movement. As illustrated by FIGS. 3, 4 and  5 , the clockwise motion of the gear  26  and the crank  25  associated therewith that engages the slot  24  of the lever  31 , causes pivotal movement the levers  31  to cause the punch blade  18  to move downwards. The punch blade  18  has a repetitious cyclical operation of any down-stroke and an upstroke. FIG. 4 shows the punch blade  18  halfway down in the down-stroke as the punch blade  18  moves towards the anvil  12 . FIG. 5 shows the punch blade  18  at its lowest position during a stapling operation. In the described embodiment, the gear  26  continues to turn clockwise, and although it has not quite completed a half of a revolution in FIG. 5, the punch blade  18  is not pushed any further down. This is because the slot  24  is non-uniformly disposed about a longitudinal axis. In other words, the slot  24  is asymmetrically disposed with respect to a longitudinal axis of the levers  31 . Accordingly, the punch blade  18  is not moved at a uniform rate up and down even if the gear  26  has a constant rotational speed. Thus, the non-uniformity of the slot  24  causes the punch blade  18  to slow down or stop moving just before the gear  26  and the crank pin  25  reaches the upper most physically possible position.  
         [0036]    The stapling cycle is completed when the gear  26  continues clockwise from the position shown in FIG. 5 to the position shown in FIG. 3. The end of Lever  31  touches the swing Lever  42  as shown in FIG. 13. The swing Lever  42  rotates about pivot axis  43  and touches the nearby leaf switch  44 . This cuts off the circuit and the stapling cycle is completed. It enabling the stapled-together sheets (not shown) to be readily withdrawn from the slot  11 . Advantageously, the punch blade carrier  19  is constrained to move down vertically by the grooves  20 . This movement is independent of the varying direction of forces applied by the end of the levers  31 . In other words, only the vertical component of the force applied by the end of the lever  22  is utilised to move the punch blade carrier  19  within the slots  20 . In at least some prior art structures isolation of the vertical force component is to achieved or is difficult to maintain. Because the vertical force component is not isolated, malfunctioning often occurs.  
         [0037]    During the downward movement of blade  18  by action of levers  31 , the staple carrier  13  pivots downwardly about pivot axis  32  to thereby close the slot  11 .  
         [0038]    Referring now to FIGS.  9  to  12 , there is shown a special press-button  39  that is used to release the staple carrier  13  and also activate a switch  40  to put motor  29  out of circuit.  
         [0039]    When the button  39  is depressed, it&#39;s associated mechanism  41  presses against the back end of staple carrier  13  to enable it to be manually withdrawn for the purpose of replacing a stable cartridge. In the withdrawn position as depicted in FIG. 11, the press button  39  stays down by action of the mechanism  41  to thereby maintain the FIG. 10 and FIG. 11-position of the switch  40 . When the staple carrier  13  is push manually back into its rest or home-position as shown in FIG. 9, the mechanism  41  pushes the push button  39  back and releases pressure from switch  40  to thereby put the electric motor  29  back in circuit for use. This is a safety feature to prevent activation of the blade  18  when the staple carrier  13  is released for staple refilling.  
         [0040]    It should be appreciated that modifications and alterations obvious to those skilled in the art are not to be considered as beyond the scope of the present invention. For example, a mechanism different to that identified at numeral  41  in FIG. 10 could be adopted. Furthermore, a paper edge-sensing switched different to the specific arrangement depicted in FIG. 8 could be adopted.