Sheet feeding device and image forming apparatus

Abstract

Provided is a sheet feeding device and an image forming apparatus capable of performing sheet feeding by electrostatic adsorption at a low noise with a simple configuration. An adsorbing member 410 includes a straight line portion 410 m and a curved portion 410 n , and the adsorbing member 410 adsorbs a sheet through the curved portion 410 n and conveys the sheet upward through the straight line portion 410 m.

1 . A sheet feeding device, comprising:
 a loading unit that loads a sheet;   a first rotating member that is arranged above the loading unit;   an adsorbing member that includes a first portion and a second portion having a curvature larger than a curvature of the first portion and electrically adsorbs the sheet loaded on the loading unit, an inner side of the adsorbing member being supported by the first rotating member;   a first nip member that nips the adsorbing member together with the first rotating member;   a first driving unit that rotates the first rotating member and the first nip member; and   a control unit that controls the driving unit,   wherein the control unit adsorbs the sheet loaded on the loading unit through the second portion and then conveys the sheet upward through the first portion.   
     
     
         2 . The sheet feeding device according to  claim 1 ,
 wherein the adsorbing member has flexibility, and is arranged to be movable to a standby position away from the sheet loaded on the loading unit, an adsorption position at which the sheet loaded on the loading unit is adsorbed, a separation position at which the adsorbed sheet moves upwards and is separated from a lower sheet, and a separation position at which the adsorbed sheet is separated from the adsorbing member.   
     
     
         3 . The sheet feeding device according to  claim 1 , further comprising,
 a second rotating member that is arranged in an upstream further than the first rotating member in a sheet feed direction;   a second nip member that nips the adsorbing member together with the second rotating member; and   a second driving unit that rotates the second rotating member and the second nip member,   wherein the control unit adsorbs the sheet loaded on the loading unit through the second portion by rotating only the second rotating member and the second nip member, and then conveys the sheet upward through the first portion by rotating only the first rotating member and the first nip member.   
     
     
         4 . The sheet feeding device according to  claim 1 ,
 wherein the first portion of the adsorbing member is formed by coupling a reinforcing member to a base member.   
     
     
         5 . The sheet feeding device according to  claim 1 ,
 wherein the first portion has substantially a straight line shape.   
     
     
         6 . The sheet feeding device according to  claim 1 , further comprising,
 a power source that applies a voltage to the adsorbing member and provides adsorption force of adsorbing the sheet by static electricity,   wherein two electrodes are arranged in the adsorbing member, and   the power source includes a first power source that applies a positive voltage to one of the two electrodes and a second power source that applies a negative voltage to the other of the two electrodes.   
     
     
         7 . The sheet feeding device according to  claim 3 ,
 wherein the two electrodes are arranged in the adsorbing member,   the power source includes a first power source that applies a positive voltage to one of the two electrodes and a second power source that applies a negative voltage to the other of the two electrodes, and   a conducting portion is formed in the first nip member or the second nip member, one of the first power source and the second power source is connected to one of the two electrodes of the adsorbing member through the conducting portion, and the other of the first power source and the second power source is connected to the other of the two electrodes of the adsorbing member through the conducting portion.   
     
     
         8 . The sheet feeding device according to  claim 1 , further comprising,
 a voltage applying member that is arranged between the adsorbing member and the power source, and abuts the adsorbing member before the adsorbing member comes into contact with the sheet, and applies a voltage from the power source to the adsorbing member.   
     
     
         9 . The sheet feeding device according to  claim 8 ,
 wherein the power source is an alternating current (AC) power source.   
     
     
         10 . The sheet feeding device according to  claim 1 ,
 wherein a magnitude of adsorption force by static electricity when bending of the adsorbing member is eliminated is set to a magnitude by which the sheet is separated from the adsorbing member due to stiffness of the sheet.   
     
     
         11 . An image forming apparatus, comprising:
 an image forming portion that forms an image on a sheet;   a loading unit that loads a sheet;   a first rotating member that is arranged above the loading unit;   an adsorbing member that includes a first portion and a second portion having a curvature larger than a curvature of the first portion and electrically adsorbs the sheet loaded on the loading unit, and inner side of the adsorbing member being supported by the first rotating member;   a first nip member that nips the adsorbing member together with the first rotating member;   a first driving unit that rotates the first rotating member and the first nip member; and   a control unit that controls the driving unit,   wherein the control unit adsorbs the sheet loaded on the loading unit through the second portion and the conveys the sheet upward through the first portion.