Paper feeding mechanism

Abstract

According to one embodiment, a paper feeding mechanism includes a tray, a first roller, a second roller, a third roller, and a guide member. The tray supports a sheet. The first roller picks up the sheet from the tray. The second roller conveys the sheet picked up by the first roller. The third roller forms a nip that sandwiches the sheet between the second roller and the third roller. Relative positions of the third roller and the first and second rollers are set such that a convey reference surface of the sheet that is in contact with the first roller and the second roller and a flat surface of the nip are disposed on substantially the same flat surface. The guide member is between the nip and the first roller and intersects the convey reference surface.

What is claimed is: 
     
         1 . A paper feeding mechanism, comprising:
 a tray that supports a sheet;   a first roller that picks up the sheet from the tray;   a second roller that conveys the sheet picked up by the first roller;   a third roller which forms a nip that sandwiches the sheet between the second roller and the third roller, the third roller having a relative position to the first roller and the second roller set such that a convey reference surface of the sheet that is in contact with the first roller and the second roller and a flat surface of the nip are disposed on substantially the same flat surface; and   a guide member between the nip and the first roller and intersects the convey reference surface.   
     
     
         2 . The paper feeding mechanism according to  claim 1 , wherein
 relative positions of a first end portion of the guide member on the upstream side of the sheet in a conveying direction and a rotary shaft of the second roller are fixed, and   relative positions of a second end portion of the guide member on the downstream side of the sheet in the conveying direction and the rotary shaft of the second roller are not fixed.   
     
     
         3 . The paper feeding mechanism according to  claim 2 , wherein
 the guide member comprises an elastic body.   
     
     
         4 . The paper feeding mechanism according to  claim 2 , wherein
 the guide member has a plate shape.   
     
     
         5 . The paper feeding mechanism according to  claim 2 , wherein
 the second end portion of the guide member has a straight line shape substantially parallel to the rotary shaft of the second roller.   
     
     
         6 . The paper feeding mechanism according to  claim 2 , further comprising:
 a support member having a first surface that guides movement of the sheet into the nip, and   the first end portion of the guide member is on an opposite side of the convey reference surface sandwiching the first surface.   
     
     
         7 . The paper feeding mechanism according to  claim 6 , wherein
 if the flat surface having the sheet which is supported by the tray and in contact with the first roller is a pick-up surface, the first surface intersects the pick-up surface, and   the second end portion of the guide member is on a same side of the nip of the pick-up surface.   
     
     
         8 . The paper feeding mechanism according to  claim 7 , wherein
 the second end portion of the guide member is on an opposite side of the pick-up surface sandwiching the first surface.   
     
     
         9 . The paper feeding mechanism according to  claim 6 , wherein
 the support member comprises a rib that protrudes toward the tray.   
     
     
         10 . The paper feeding mechanism according to  claim 6 , with the proviso that the support member does not have a rib on the first surface. 
     
     
         11 . An image forming apparatus comprising the paper feeding mechanism according to  claim 1 . 
     
     
         12 . A method of feeding paper without a squeal sound, comprising:
 supporting a sheet with a tray;   picking up the sheet from the tray with a first roller;   conveying the sheet picked up by the first roller with a second roller;   forming a nip that sandwiches the sheet between the second roller and a third roller, the third roller having a relative position to the first roller and the second roller such that a convey reference surface of the sheet that is in contact with the first roller and the second roller and a flat surface of the nip are disposed on substantially the same flat surface; and   guiding the sheet using a guide member positioned between the nip and the first roller and intersecting the convey reference surface.   
     
     
         13 . The method of feeding paper according to  claim 12 , wherein
 relative positions of a first end portion of the guide member on the upstream side of the sheet in a conveying direction and a rotary shaft of the second roller are fixed, and   relative positions of a second end portion of the guide member on the downstream side of the sheet in the conveying direction and the rotary shaft of the second roller are not fixed.   
     
     
         14 . The method of feeding paper according to  claim 13 , wherein
 the guide member comprises an elastic body.   
     
     
         15 . The method of feeding paper according to  claim 13 , wherein
 the guide member has a plate shape.   
     
     
         16 . The method of feeding paper according to  claim 13 , wherein
 the second end portion of the guide member has a straight line shape substantially parallel to the rotary shaft of the second roller.   
     
     
         17 . The method of feeding paper according to  claim 13 , further comprising:
 that guiding movement of the sheet into the nip using a first surface of a support member, and   the first end portion of the guide member is on an opposite side of the convey reference surface sandwiching the first surface.   
     
     
         18 . A quiet paper feeder, comprising:
 a tray that supports a plurality of sheets;   a first roller that picks up a sheet from the tray;   a second roller that conveys the sheet picked up by the first roller;   a third roller which forms a nip that sandwiches the sheet between the second roller and the third roller, the third roller having a relative position to the first roller and the second roller set such that a convey reference surface of the sheet that is in contact with the first roller and the second roller and a flat surface of the nip are disposed on substantially the same flat surface; and   a guide member between the nip and the first roller and intersects the convey reference surface.   
     
     
         19 . The quiet paper feeder according to  claim 18 , wherein
 relative positions of a first end portion of the guide member on the upstream side of the sheet in a conveying direction and a rotary shaft of the second roller are fixed, and   relative positions of a second end portion of the guide member on the downstream side of the sheet in the conveying direction and the rotary shaft of the second roller are not fixed.   
     
     
         20 . The quiet paper feeder according to  claim 19 , wherein
 the guide member comprises an elastic body and has a plate shape.