Patent ID: 8503039

Claim:
An image reading apparatus, comprising: a transparent member provided at a reading position on a conveying path of a document; a reading mechanism for reading, through said transparent member, the document conveyed along said conveying path and passing through said reading position; a white reference member provided such that a position of said white reference member with respect to said transparent member is variable, for being read by said reading mechanism through said transparent member to obtain a reference value used in shading correction in said reading mechanism; an elastic member provided such that a position of said elastic member with respect to said transparent member is variable, for coming into contact with a surface of said transparent member facing toward said conveying path and cleaning the surface when said elastic member is located at a position where said elastic member faces said transparent member; and a controller for controlling the respective positions of said white reference member and said elastic member with respect to said transparent member and calculating said reference value, wherein said controller controls the positions of said white reference member and said elastic member to alternately achieve movement of said white reference member to a position where said white reference member faces said transparent member and movement of said elastic member to the position where said elastic member faces said transparent member, and calculates said reference value using a plurality of detection values obtained by reading said white reference member by means of said reading mechanism when said white reference member is located at the position where said white reference member faces said transparent member, before and after said elastic member moves to the position where said elastic member faces said transparent member.