Document transport device including slider that moves between connected position for transmitting rotational force to sheet feeding roller, and separated position for disconnecting transmission of rotational force to sheet feeding roller

Abstract

A document transport device includes a document tray, an actuator, a delivery roller, a rotary shaft, a sheet feeding roller, a separation member, a slider movable along the rotary shaft, between a connected position where the slider is linked with the sheet feeding roller to transmit rotational force thereto, and a separated position where the slider is spaced from the sheet feeding roller, thereby disconnecting transmission of the rotational force to the sheet feeding roller, and an operation lever rotatably supporting the slider, and configured to move parallel to an axial direction of the rotary shaft, when the actuator rotates. When no document is on the document tray and the actuator is not rotating, the operation lever moves the slider to the separated position, and when the document is placed on the document tray and the actuator rotates, the operation lever moves, thereby moving the slider to the connected position.

What is claimed is: 
     
         1 . A document transport device comprising:
 a document tray;   an actuator to be made to rotate when a document is placed on the document tray;   a delivery roller that delivers the document;   a rotary shaft that rotates by being driven;   a sheet feeding roller that transports the document delivered by the delivery roller, upon being made to rotate by rotational force of the rotary shaft;   a separation member that defines a separation nip by abutting against the sheet feeding roller;   a slider supported so as to move along the rotary shaft, between a connected position where the slider is connected to the sheet feeding roller, to transmit rotational force to the sheet feeding roller, and a separated position where the slider is separated from the sheet feeding roller, to disconnect transmission of the rotational force from the rotary shaft to the sheet feeding roller;   an operation lever rotatably supporting the slider, and configured to move parallel to an axial direction of the rotary shaft, when the actuator rotates,   wherein, when no document is on the document tray and the actuator is not rotating, the operation lever moves the slider to the separated position, and   when the document is placed on the document tray and the actuator rotates, the operation lever moves, thereby moving the slider to the connected position.   
     
     
         2 . The document transport device according to  claim 1 , further comprising a link lever provided between the actuator and the operation lever, and configured to convert a rotating motion of the actuator into a reciprocating motion of the operation lever along the parallel direction. 
     
     
         3 . The document transport device according to  claim 1 , further comprising:
 a transmission gear fixed to the rotary shaft; and   a coupling provided between the transmission gear and the slider, so as to move along the rotary shaft, and to rotate interlocked with the transmission gear,   wherein the slider is connected to the coupling, and connected to the sheet feeding roller, in the connected position.   
     
     
         4 . The document transport device according to  claim 1 ,
 wherein the sheet feeding roller and the slider are connected to each other via a ratchet mechanism, in the connected position.   
     
     
         5 . The document transport device according to  claim 1 ,
 wherein a circumferential speed of the sheet feeding roller is faster than a circumferential speed of the transmission gear.