Sheet feeding apparatus and image forming apparatus

Abstract

A sheet feeding apparatus includes: a sheet containing device for housing sheets; a sheet feeding roller that feed the sheets contained in the sheet containing device; a pushing member for pushing the sheets contained in the sheet containing device against the sheet feeding roller; a separation pad which is provided so as to be capable of abutting against the sheet feeding roller and separates the sheets one by one as the sheets are fed by the sheet feeding roller and the pushing member; and a sheet guide portion arranged between a pushing portion where the sheets are pushed against the sheet feeding roller by the pushing member and an abutting portion where the sheet feeding roller and the separation pad come into abutment against each other. As a result, a sheet feeding apparatus with reduced noise can be realized. In addition, an image forming apparatus with silent operation can be realized by using the sheet feeding apparatus.

1 . A sheet feeding apparatus comprising: 
 sheet containing means for containing sheets;    a sheet feeding roller for feeding the sheets contained in said sheet containing means;    pushing means for pushing the sheets contained in said sheet containing means against said sheet feeding roller;    a separation pad which is provided at a position to be capable of abutting against the sheet feeding roller and separates the sheets one by one as the sheets are fed by the sheet feeding roller and said pushing means; and    a sheet guide portion arranged between a pushing portion where the sheets are pushed against the sheet feeding roller by said pushing means and an abutting portion where the sheet feeding roller and the separation pad come into abutment against each other.    
   
   
       2 . A sheet feeding apparatus according to  claim 1 , 
 wherein the sheet guide portion is formed integrally with said sheet containing means.    
   
   
       3 . A sheet feeding apparatus according to  claim 1 , 
 wherein the sheet guide portion has as inclined surface that is inclined from the pushing portion where the sheets are pushed against the sheet feeding roller by said pushing means, toward the abutting portion where the sheet feeding roller and the separation pad come into abutment against each other.    
   
   
       4 . A sheet feeding apparatus according to  claim 1 , 
 wherein the sheet guide portion has an arc shape with an inner diameter surface thereof serving as a sheet guide.    
   
   
       5 . A sheet feeding apparatus according to  claim 1 , wherein said pushing means rotates about its rotation center to push the sheets against the sheet feeding roller and is arranged with respect to the sheet feeding roller such that a tangent direction of the pushing portion, where the sheets are pushed against the sheet feeding roller by said pushing means, and a direction of a surface on which the sheets pushed against the sheet feeding roller by said pushing means are stacked, coincide with each other.  
   
   
       6 . A sheet feeding apparatus according to  claim 1 , 
 wherein, when it is assumed that an angle formed by a tangent of the pushing portion, where the sheets are pushed against the sheet feeding roller by said pushing means, and a guide surface of the sheet guide portion is α, and an angle formed by the guide surface of the sheet guide portion and a nip line of the abutting portion, where the sheet feeding roller and the separation pad come into abutment against each other, is β, the angles α and β respectively satisfy a relation of 110°≦α≦135° and a relation of 170°≦β≦175°   
   
   
       7 . A sheet feeding apparatus according to  claim 6 , 
 wherein the separation pad includes a separating member formed of a rubber material and coming into abutment against the sheet feeding roller to separate the sheets, and a retaining member that retains the separating member, and wherein the sheet guide portion is formed integrally on an upstream side in a sheet conveying direction of the retaining member.    
   
   
       8 . A sheet feeding apparatus according to  claim 1 , 
 wherein, when it is assumed that a coefficient of friction between a guide surface of the sheet guide portion and the sheets is μ1, a coefficient of friction between the separation pad and the sheets is μ2, and a coefficient of friction between the sheet feeding roller and the sheets is μ3, the coefficients of friction satisfies a relation of μ1<μ2<μ3.    
   
   
       9 . A sheet feeding apparatus according to  claim 1 , 
 wherein a guide surface of the sheet guide surface is made of metal, and the sheet guide portion is grounded.    
   
   
       10 . A sheet feeding apparatus comprising: 
 a sheet feeding cassette;    a sheet feeding roller which comes into abutment against sheets stacked on an intermediate plate provided in a cassette main body of the sheet feeding cassette and rotates to feed the sheets;    a separation pad which is provided at a position to be capable of abutting against the sheet feeding roller and separates the sheets one by one as the sheets are delivered by said sheet feeding roller; and    a sheet guide portion which is located between a pushing portion, where the sheets are pushed against the sheet feeding roller, and an abutting portion where said sheet feeding roller and the separation pad come into abutment against each other, and is formed integrally with the cassette main body.    
   
   
       11 . A sheet feeding apparatus according to  claim 9 , 
 wherein, when it is assumed that an angle formed by a tangent of the pushing portion, where the sheets are pushed against the sheet feeding roller by said pushing means, and a guide surface of the sheet guide portion is α, and an angle formed by the guide surface of the sheet guide portion and a nip line of the abutting portion, where the sheet feeding roller and the separation pad come into abutment against each other, is β, the angles α and β respectively satisfy a relation of 110°≦α≦135° and a relation of 170°≦β≦ 175 °   
   
   
       12 . A sheet feeding apparatus according to  claim 9 , 
 wherein, when it is assumed that a coefficient of friction between a guide surface of the sheet guide portion and the sheets is μ1, a coefficient of friction between the separation pad and the sheets is μ2, and a coefficient of friction between the sheet feeding roller and the sheets is μ3, the coefficients of friction satisfies a relation of μ1<μ2<μ3.    
   
   
       13 . An image forming apparatus comprising: 
 the sheet feeding apparatus according to any one of  claims 1  to  12 ; and    an image forming portion that forms an image on the sheets delivered from the sheet feeding apparatus.