Paper feeding apparatus, image forming apparatus, and paper feeding method

Abstract

A paper feeding apparatus according to an embodiment includes: a pick-up roller that picks up stacked sheets; a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the stacked sheets; and an elevation control unit that elevates the stopper guide by interlocking with elevation of the pick-up roller.

1 . A paper feeding apparatus comprising:
 a pick-up roller that picks up stacked sheets;   a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the stacked sheets; and   an elevation control unit that elevates the stopper guide by interlocking with elevation of the pick-up roller.   
     
     
         2 . The apparatus according to  claim 1 , wherein the elevation control unit elevates the stopper guide so that a difference between a stack height of the sheets and a height of a top surface of the stopper guide is in a predetermined range. 
     
     
         3 . The apparatus according to  claim 1 , wherein the elevation control unit elevates the stopper guide so that the number of sheets picked up by the pick-up roller is equal to or smaller than a predetermined number. 
     
     
         4 . The apparatus according to  claim 1 , wherein the elevation control unit includes:
 a pick-up arm that supports the pick-up roller;   an elevation solenoid that controls elevation of a portion that pushes the pick-up arm up or moves the pick-up arm down; and   a lever of which one end abuts on the portion elevated by the elevation solenoid, and of which the other end includes the stopper guide, so as to rotate about a predetermined fulcrum.   
     
     
         5 . The apparatus according to  claim 4 , wherein the pick-up roller is lowered when the portion is moved upward, and is lifted when the portion is moved downward. 
     
     
         6 . The apparatus according to  claim 1 , wherein the elevation control unit moves the stopper guide upward when the pick-up roller is moved upward, and moves the stopper guide downward when the pick-up roller is moved downward. 
     
     
         7 . The apparatus according to  claim 1 , wherein the side wall of the stopper guide that abuts on the sheets is provided with a gradient such that a lower side of the side wall further deviates to a stack side of the sheets than an upper side thereof. 
     
     
         8 . An image forming apparatus comprising:
 an image forming section that forms an image on a sheet;   a tray on which the sheets are stacked;   a pick-up roller that picks up the sheets stacked on the tray and transports the sheets to the image forming section;   a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the sheets stacked on the tray; and   an elevation control unit that elevates the stopper guide by interlocking with elevation of the pick-up roller.   
     
     
         9 . The apparatus according to  claim 8 , wherein the elevation control unit elevates the stopper guide so that a difference between a stack height of the sheets and a height of a top surface of the stopper guide is in a predetermined range. 
     
     
         10 . The apparatus according to  claim 8 , wherein the elevation control unit elevates the stopper guide so that the number of sheets picked up by the pick-up roller is equal to or smaller than a predetermined number. 
     
     
         11 . The apparatus according to  claim 8 , wherein the elevation control unit includes:
 a pick-up arm that supports the pick-up roller;   an elevation solenoid that controls elevation of a portion that pushes the pick-up arm up or moves the pick-up arm down; and   a lever of which one end abuts on the portion elevated by the elevation solenoid, and of which the other end includes the stopper guide, so as to rotate about a predetermined fulcrum.   
     
     
         12 . The apparatus according to  claim 11 , wherein the pick-up roller is lowered when the portion is moved upward, and is lifted when the portion is moved downward. 
     
     
         13 . The apparatus according to  claim 8 , wherein the elevation control unit moves the stopper guide upward when the pick-up roller is moved upward, and moves the stopper guide downward when the pick-up roller is moved downward. 
     
     
         14 . The apparatus according to  claim 8 , wherein the side wall of the stopper guide that abuts on the sheets is provided with a gradient such that a lower side of the side wall further deviates to a stack side of the sheets than an upper side thereof. 
     
     
         15 . A paper feeding method of an image forming apparatus,
 wherein a paper feeding apparatus of the image forming apparatus includes   a pick-up roller that picks up stacked sheets, and   a stopper guide of which a side wall abuts on front ends of the sheets at least at a lower layer in a transport direction from among the stacked sheets,   the method includes elevating the stopper guide by interlocking with elevation of the pick-up roller.   
     
     
         16 . The method according to  claim 15 , wherein the paper feeding apparatus elevates the stopper guide so that a difference between a stack height of the sheets and a height of a top surface of the stopper guide is in a predetermined range. 
     
     
         17 . The method according to  claim 15 , wherein the paper feeding apparatus elevates the stopper guide so that the number of sheets picked up by the pick-up roller is equal to or smaller than a predetermined number. 
     
     
         18 . The method according to  claim 15 , wherein the paper feeding apparatus elevates the stopper guide by interlocking with elevation of the pick-up roller by using:
 a pick-up arm that supports the pick-up roller;   an elevation solenoid that controls elevation of a portion that pushes the pick-up arm up or moves the pick-up arm down; and   a lever of which one end abuts on the portion elevated by the elevation solenoid, and of which the other end includes the stopper guide, so as to rotate about a predetermined fulcrum.   
     
     
         19 . The method according to  claim 18 , wherein the pick-up roller is lowered when the portion is moved upward, and is lifted when the portion is moved downward. 
     
     
         20 . The method according to  claim 15 , wherein the side wall of the stopper guide that abuts on the sheets is provided with a gradient such that a lower side of the side wall further deviates to a stack side of the sheets than an upper side thereof.