Document conveying devices and image reading devices comprising such document conveying devices

Abstract

A document conveying device includes a conveying path and a feed unit. The feed unit includes a tray including a document positioning surface configured to receive documents thereon, in which the document positioning surface has a hole formed therethrough. The feed unit also includes a separation roller which is rotatably supported by a drive shaft extending in a direction orthogonal to a document conveying direction and is configured to contact an uppermost document of the documents and to separate and convey the uppermost document. The separation roller includes a first end and a second end opposite the first end. Moreover, the feed unit includes a document sensor including a detection portion configured to detect the documents and to selectively move between a first position in which the detection portion projects from the document positioning surface via the hole and a second position in which the detection portion is retracted from the document positioning surface via the hole. In addition, the feed unit includes a casing pivotably mounted on the drive shaft. The casing includes a plate extending adjacent to the first end of the separation roller in the document conveying direction, and the first end of the separation roller and the detection portion are positioned closer to the second end of the separation roller than the plate of the casing.

1 . A document conveying device comprising:
 a conveying path; and   a feed unit comprising:
 a tray comprising a document positioning surface configured to receive at least one document thereon, wherein the document positioning surface has a hole formed therethrough; 
 a separation roller which is rotatably supported by a drive shaft extending in a direction orthogonal to a document conveying direction and is configured to contact an uppermost document of the at least one document positioned on the document positioning surface and to separate and convey the uppermost document along the conveying path in the document conveying direction, wherein the separation roller comprises a first end and a second end opposite the first end; 
 a document sensor comprising a detection portion configured to detect the at least one document positioned on the document positioning surface, and to selectively move between a first position in which the detection portion projects from the document positioning surface via the hole and a second position in which the detection portion is retracted from the document positioning surface via the hole; and 
 a casing pivotably mounted on the drive shaft, wherein the casing comprises a plate extending adjacent to the first end of the separation roller in the document conveying direction, and the first end of the separation roller and the detection portion are positioned closer to the second end of the separation roller than the plate of the casing. 
   
     
     
         2 . The document conveying device of  claim 1 , wherein the separation roller comprises a first side and a second side opposite the first side, and the casing has an opening formed therethrough, wherein the separation roller is exposed to face the document positioning surface via the opening, and the casing is configured to cover at least the first side of the separation roller, wherein the second side of the separation roller faces the document positioning surface, and the casing extends over the detection portion. 
     
     
         3 . The document conveying device of  claim 1 , wherein a lower edge of the plate of the casing is positioned closer to the document positioning surface than the drive shaft is positioned to the document positioning surface. 
     
     
         4 . The document conveying device of  claim 1 , wherein the detection portion is positioned between the first end of the separation roller and the plate of the casing. 
     
     
         5 . The document conveying device of  claim 1 , wherein the separation roller and the casing are aligned with a first center line of the document positioning surface in a predetermined direction which is orthogonal to the document conveying direction, and are unaligned with a second center line of the document positioning surface in the document conveying direction. 
     
     
         6 . The document conveying device of  claim 5 , wherein the first end of the separation roller and the detection portion are positioned closer to the first center line of the document positioning surface than the plate of the casing. 
     
     
         7 . The document conveying device of  claim 1 , wherein the casing extends upstream from the drive shaft in the document conveying direction, and the document conveying device further comprises a pick-up roller rotatably coupled to the casing at an upstream side of the separation roller in the document conveying direction, wherein the pick-up roller is configured to contact the uppermost document. 
     
     
         8 . The document conveying device of  claim 7 , wherein the detection portion is positioned downstream of the pick-up roller and upstream of the separation roller in the document conveying direction. 
     
     
         9 . The document conveying device of  claim 1 , further comprising a cover configured to selectively move between an open position and a closed position in which the cover covers at least a downstream region of the tray in the document conveying direction, wherein the cover extends over the casing when the cover is in the closed position. 
     
     
         10 . An image reading device comprising:
 a document conveying device comprising:
 a conveying path; and 
 a feed unit comprising:
 a tray comprising a document positioning surface configured to receive at least one document thereon, wherein the document positioning surface has a hole formed therethrough; 
 a separation roller which is rotatably supported by a drive shaft extending in a direction orthogonal to a document conveying direction and is configured to contact an uppermost document of the at least one document positioned on the document positioning surface and to separate and convey the uppermost document along the conveying path in the document conveying direction, wherein the separation roller comprises a first end and a second end opposite the first end; 
 a document sensor comprising a detection portion configured to detect the at least one document positioned on the document positioning surface, and to selectively move between a first position in which the detection portion projects from the document positioning surface via the hole and a second position in which the detection portion is retracted from the document positioning surface via the hole; and 
 a casing pivotably mounted on the drive shaft, wherein the casing comprises a plate extending adjacent to the first end of the separation roller in the document conveying direction, and the first end of the separation roller and the detection portion are positioned closer to the second end of the separation roller than the plate of the casing.