Sheet transporting device, image reading device, and image forming apparatus

Abstract

A sheet transporting device includes: a sheet receiver that receives a sheet and that includes a first detector that detects a size of the sheet in a transport direction; a sheet transport member that transports the sheet received on the sheet receiver to an image read position along a sheet transport path; and a second detector disposed in front of the image read position on the sheet transport path to detect whether any sheet is present. The second detector determines whether the sheet received on the sheet receiver has a size smaller than or equal to a predetermined length in the transport direction.

What is claimed is: 
     
         1 . A sheet transporting device, comprising:
 a sheet receiver that receives a sheet and that includes a first detector that detects a size of the sheet in a transport direction;   a sheet transport member that transports the sheet received on the sheet receiver to an image read position along a sheet transport path; and   a second detector disposed in front of the image read position on the sheet transport path to detect whether any sheet is present,   wherein the second detector determines whether the sheet received on the sheet receiver has a size smaller than or equal to a predetermined length in the transport direction.   
     
     
         2 . The sheet transporting device according to  claim 1 , wherein the second detector is disposed most upstream at the sheet transport path in the sheet transport direction. 
     
     
         3 . The sheet transporting device according to  claim 2 , wherein the predetermined length is shorter than a length along the sheet transport path from the second detector to the image read position. 
     
     
         4 . The sheet transporting device according to  claim 1 , wherein the first detector detects that the sheet received on the sheet receiver has a larger size than a length of an A4 size in a longitudinal direction. 
     
     
         5 . The sheet transporting device according to  claim 4 , wherein whether the size of the sheet is smaller than or equal to the predetermined length is determined based on whether a trailing end of the sheet has passed the second detector before a leading end of the sheet arrives at the image read position. 
     
     
         6 . The sheet transporting device according to  claim 5 , wherein whether the size of the sheet is smaller than or equal to the predetermined length is determined simply when the first detector does not detect the sheet received on the sheet receiver. 
     
     
         7 . An image reading device, comprising:
 an image reading member that reads an image on a sheet; and   a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,   wherein the sheet transporting device according to  claim 1  is used as the sheet transport member.   
     
     
         8 . An image reading device, comprising:
 an image reading member that reads an image on a sheet; and   a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,   wherein the sheet transporting device according to  claim 2  is used as the sheet transport member.   
     
     
         9 . An image reading device, comprising:
 an image reading member that reads an image on a sheet; and   a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,   wherein the sheet transporting device according to  claim 3  is used as the sheet transport member.   
     
     
         10 . An image reading device, comprising:
 an image reading member that reads an image on a sheet; and   a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,   wherein the sheet transporting device according to  claim 4  is used as the sheet transport member.   
     
     
         11 . An image reading device, comprising:
 an image reading member that reads an image on a sheet; and   a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,   wherein the sheet transporting device according to  claim 5  is used as the sheet transport member.   
     
     
         12 . An image reading device, comprising:
 an image reading member that reads an image on a sheet; and   a sheet transport member that transports the sheet to a read position where the image reading member reads the image on the sheet,   wherein the sheet transporting device according to claim  6  is used as the sheet transport member.   
     
     
         13 . An image forming apparatus, comprising:
 the image reading device according to claim  7  that reads an image on a sheet; and   an image recording device that records the image on the sheet read by the image reading device on a recording medium.   
     
     
         14 . An image forming apparatus, comprising:
 the image reading device according to claim  8  that reads an image on a sheet; and   an image recording device that records the image on the sheet read by the image reading device on a recording medium.   
     
     
         15 . An image forming apparatus, comprising:
 the image reading device according to claim  9  that reads an image on a sheet; and   an image recording device that records the image on the sheet read by the image reading device on a recording medium.   
     
     
         16 . An image forming apparatus, comprising:
 the image reading device according to claim  10  that reads an image on a sheet; and   an image recording device that records the image on the sheet read by the image reading device on a recording medium.   
     
     
         17 . An image forming apparatus, comprising:
 the image reading device according to claim  11  that reads an image on a sheet; and   an image recording device that records the image on the sheet read by the image reading device on a recording medium.   
     
     
         18 . An image forming apparatus, comprising:
 the image reading device according to claim  12  that reads an image on a sheet; and   an image recording device that records the image on the sheet read by the image reading device on a recording medium.   
     
     
         19 . A sheet transporting device, comprising:
 sheet receiving means for receiving a sheet and including first detection means for detecting a size of the sheet in a transport direction;   sheet transport means for transporting the sheet received on the sheet receiving means to an image read position along a sheet transport path; and   second detection means disposed in front of the image read position on the sheet transport path for detecting whether any sheet is present,   wherein the second detection means determines whether the sheet received on the sheet receiving means has a size smaller than or equal to a predetermined length in the transport direction.