Sheet feeding apparatus and image forming apparatus

Abstract

A sheet feeding apparatus includes a first and second electrode elements arranged on an attracting member, including a plurality of attracting force generation electrodes and power feeding electrodes corresponding to the respective attracting force generation electrodes. The attracting force generation electrodes of the first and second electrode elements are alternately arranged. Further, the sheet feeding apparatus includes a power feeding brush arranged at a position different from an attracting position and capable of supplying voltages to the electrode elements, respectively, and a neutralization roller pair arranged at a position different from the attracting position and the power feeding brush and configured to be brought into contact with the electrode elements to remove a residual charge on the attracting member. With this, decrease in productivity is prevented by enabling both of the generation of the electrostatic attracting force and the neutralization without control of switching between power feeding and neutralization.

1 . A sheet feeding apparatus, comprising:
 a stacking unit on which a sheet is stacked;   a first rotary member provided on an upside of the stacking unit;   a second rotary member provided on a downstream in a sheet feeding direction with respect to the first rotary member;   an endless attracting member configured to rotate in a peripheral direction of the endless attracting member whose inner surface is supported by the first rotary member and the second rotary member and to feed the sheet by attracting the sheet at an attracting position opposed to the sheet stacked on the stacking unit;   a first electrode element and a second electrode element that are provided on the endless attracting member, the first electrode element and the second electrode element each including a plurality of attracting force generation electrodes and a plurality of power feeding electrodes, each of the attracting force generation electrodes connected to each of attracting force generation electrodes to correspond with each other, the plurality of attracting force generation electrodes of the first electrode element and the plurality of attracting force generation electrodes of the second electrode element being alternately provided to be spaced with each other in the peripheral direction of the endless attracting member;   a power feeding unit provided at a position different from the attracting position and capable of supplying a positive voltage and a negative voltage to the first electrode element and the second electrode element, respectively; and   a neutralization unit provided at a position different from the attracting position and the power feeding unit and configured to be brought into contact with the first electrode element and the second electrode element to remove a residual charge on the endless attracting member,   wherein the first electrode element and the second electrode element each comprise connecting lines configured to connect the plurality of attracting force generation electrodes to the power feeding electrodes corresponding to the respective plurality of attracting force generation electrodes so as to lie next to each other in a width direction perpendicular to the peripheral direction at positions different from each other in the peripheral direction, and   wherein the plurality of attracting force generation electrodes of each of the first electrode element and the second electrode element are configured to move to the attracting position along with rotation of the endless attracting member by feeding power from the power feeding unit through each of the power feeding electrodes corresponding thereto, so that each of the attracting force generation electrodes generates an electrostatic attracting force.   
     
     
         2 . A sheet feeding apparatus according to  claim 1 , wherein the plurality of attracting force generation electrodes of the first electrode element and the plurality of attracting force generation electrodes of the second electrode element are configured to alternately extend in a pectinate manner from the respective power feeding electrodes in the width direction perpendicular to the peripheral direction of the endless attracting member. 
     
     
         3 . A sheet feeding apparatus according to  claim 1 , wherein the power feeding unit comprises a power feeding brush configured to be brought into contact with the power feeding electrodes to feed power thereto. 
     
     
         4 . A sheet feeding apparatus according to  claim 3 , further comprising a tension providing unit configured to provide a tension to the endless attracting member so as to be capable of maintaining constant a contact pressure of the power feeding brush to the power feeding electrodes provided to be opposed to the power feeding brush in the endless attracting member. 
     
     
         5 . A sheet feeding apparatus according to  claim 4 ,
 wherein the neutralization unit comprises a neutralization roller pair configured to nip the endless attracting member in a form of being extended in the width direction perpendicular to the peripheral direction of the endless attracting member, and   wherein the tension providing unit is configured to apply a load to the neutralization roller pair so as to apply, to the endless attracting member, a load in a direction opposite to a rotating direction of the endless attracting member, to thereby provide a tension to the power feeding electrodes and the connecting lines.   
     
     
         6 . A sheet feeding apparatus according to  claim 4 , wherein the tension providing unit comprises a plate member provided on an inner peripheral side of the endless attracting member and configured to press the power feeding electrodes to the power feeding brush. 
     
     
         7 . A sheet feeding apparatus according to  claim 1 , wherein at least the power feeding electrodes of each of the first electrode element and the second electrode element are provided so as to be exposed on an outer peripheral surface of the endless attracting member. 
     
     
         8 . A sheet feeding apparatus according to  claim 1 ,
 wherein at least the power feeding electrodes of each of the first electrode element and the second electrode element are provided so as to be exposed on an inner peripheral surface of the endless attracting member, and   wherein the power feeding unit comprises at least one of the first rotary member or the second rotary member, and is configured to be brought into contact with the power feeding electrodes exposed on the inner peripheral surface to feed power thereto.   
     
     
         9 . A sheet feeding apparatus according to  claim 1 , wherein, under a state in which a plurality of the attracting force generation electrodes of each of the first electrode element and the second electrode element are electrically conducted with each other, the plurality of the attracting force generation electrodes are connected to corresponding one of the connecting lines. 
     
     
         10 . A sheet feeding apparatus according to  claim 1 , further comprising:
 a first nipping member configured to nip the endless attracting member together with the first rotary member;   a second nipping member configured to nip the endless attracting member together with the second rotary member;   a first driving unit and a second driving unit configured to drive the first rotary member and the second rotary member, respectively; and   a control unit configured to control the first driving unit and the second driving unit,   wherein the control unit is configured to:
 control each of the first driving unit and the second driving unit so as to provide a difference in a rotational speed between the first rotary member and the second rotary member, to thereby increase an amount that the endless attracting member sags downward to attract the sheet on the stacking unit to the endless attracting member; and then 
 feed the sheet attracted to the endless attracting member while decreasing the amount that the endless attracting member sags downward. 
   
     
     
         11 . A sheet feeding apparatus according to  claim 1 ,
 wherein the connecting lines are respectively extended from the plurality of attracting force generation electrodes to an upstream side in the rotating direction of the endless attracting member,   wherein the power feeding unit is provided on the upstream side in the rotating direction of the endless attracting member with respect to the attracting position, and   wherein the neutralization unit is provided on a downstream side in the rotating direction of the endless attracting member with respect to the attracting position.   
     
     
         12 . A sheet feeding apparatus according to  claim 11 , wherein the connecting lines are each set to have such a length that the plurality of attracting force generation electrodes moving from the attracting position toward the neutralization unit are separated from the power feeding unit before reaching the neutralization unit. 
     
     
         13 . A sheet feeding apparatus according to  claim 1 , wherein the power feeding electrodes includes the connecting lines. 
     
     
         14 . An image forming apparatus, comprising:
 an image forming unit configured to form an image on a sheet; and   a sheet feeding apparatus of  claim 1 .   
     
     
         15 . An image forming apparatus, comprising:
 an image forming unit configured to form an image on a sheet; and   a sheet feeding apparatus of  claim 2 .   
     
     
         16 . An image forming apparatus, comprising:
 an image forming unit configured to form an image on a sheet; and   a sheet feeding apparatus of  claim 3 .   
     
     
         17 . An image forming apparatus, comprising:
 an image forming unit configured to form an image on a sheet; and   a sheet feeding apparatus of  claim 4 .   
     
     
         18 . An image forming apparatus, comprising:
 an image forming unit configured to form an image on a sheet; and   a sheet feeding apparatus of  claim 5 .   
     
     
         19 . An image forming apparatus, comprising:
 an image forming unit configured to form an image on a sheet; and   a sheet feeding apparatus of  claim 6 .   
     
     
         20 . An image forming apparatus, comprising:
 an image forming unit configured to form an image on a sheet; and   a sheet feeding apparatus of  claim 7 .