Document conveying device

Abstract

A document conveying device includes a feed roller, a separation pad, a pad holder, a tension spring, and a separation pad support mechanism. The feed roller and the separation pad form a separation nip at which a sheet is separated and conveyed. The pad holder holds the separation pad and can be turned upward and downward around a turning shaft. The tension spring biases the pad holder upward to press the separation pad against the feed roller. The separation pad support mechanism turns the pad holder in a direction to separate the separation pad from the feed roller against a biasing force of the tension spring.

1 . A document conveying device comprising:
 a feed roller and a separation pad which forms a separation nip at which a sheet is separated and conveyed;   a pad holder which holds the separation pad and can be turned upward and downward around a turning shaft;   a tension spring which biases the pad holder upward to press the separation pad against the feed roller; and   a separation pad support mechanism which turns the pad holder in a direction to separate the separation pad from the feed roller against a biasing force of the tension spring.   
     
     
         2 . The document conveying device according to  claim 1 , wherein
 the separation pad support mechanism includes:   a rotating member which is rotatably supported around an axis parallel to the turning shaft of the pad holder and to which one end of the tension spring is connected;   a link bar which couples the rotating member to the turning shaft of the pad holder; and   a driving member which rotates the rotating member, wherein   during normal sheet feeding, the rotating member is pulled by the tension spring and rotates in one direction to rotate the pad holder upward via the link bar to press the separation pad against the sheet feed roller, and   when a sheet jam occurs at the separation nip, the driving member rotates the rotating member in an opposite direction against the biasing force of the tension spring and turns the pad holder downward via the link bar to separate the separation pad from the feed roller.   
     
     
         3 . The document conveying device according to  claim 2 , comprising:
 a conveying roller which is disposed downstream of the separation nip in the sheet conveyance direction, and   a conveying gear which can rotate integrally with the conveying roller and can rotate with respect to the conveying roller within a certain angle, wherein   the driving member is provided with a driving gear which is engaged with the conveying gear.   
     
     
         4 . The document conveying device according to  claim 3 , wherein
 the separation pad support mechanism includes a ratchet mechanism which transmits a rotation of the driving gear to the rotating member when the driving gear rotates in one direction and does not transmit the rotation of the driving gear to the rotating member when the driving gear rotates in the other direction, wherein   when the conveying gear rotates so that the conveying roller rotates in the direction in which the conveying roller conveys the document, the driving gear rotates in the other direction and the rotation of the driving gear is not transmitted to the rotating member by the ratchet mechanism, and when the conveying gear rotates in the opposite direction, the driving gear rotates in one direction and the rotation of the driving gear is transmitted to the rotating member by the ratchet mechanism and the rotating member rotates in the opposite direction.   
     
     
         5 . The document conveying device according to  claim 4 , wherein
 the conveying gear rotates within the angle in the opposite direction with respect to the conveying roller.   
     
     
         6 . The document conveying device according to  claim 1 , wherein
 the tension spring and the separation pad holding mechanism are disposed outside a document conveying region.