Image reading apparatus, image reading unit thereof, and reference member thereof for shading correction

Abstract

An image reading apparatus which is capable of performing accurate shading correction with simple arrangement while preventing a reference member from being scratched and paper powder and the like dust from being deposited on the reference member. The image reading apparatus comprises an image reading unit. In the image reading unit, a contact glass guides an original on an image reading location. The contact glass is held by a glass holding member. A line image sensor reads the image on the original conveyed on the image reading location, through the contact glass. The image reading unit further comprises a reference member whose image is readable by the image sensor, and a moving mechanism to move the image sensor so as to enable the image sensor to alternatively read the original and a reference surface of the reference member.

1 . An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising:
 an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move said image sensor so as to enable said image sensor to read alternatively the original conveyed on the image reading location and said reference member,   wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path.   
   
   
       2 . An image reading apparatus according to  claim 1 , wherein the reference surface of said reference member is held in close contact with said contact glass. 
   
   
       3 . An image reading apparatus according to  claim 1 , wherein said reference member is disposed on said glass holding member. 
   
   
       4 . An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising:
 an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,   wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path, and said reference member is disposed on an original conveying path-side surface of said contact glass.   
   
   
       5 . An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising:
 an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,   wherein arrangement of said image sensor and said reference member is so designed as to make a reference surface of said reference member isolated from the conveying path, and said reference member is fixed to an opposite surface of an original conveying path-side surface of said contact glass.   
   
   
       6 . An image reading apparatus configured to read an image formed on an original, while conveying the original along a conveying path, comprising:
 an image reading unit including a contact glass configured to guide an original to an image reading location, a glass holding member configured to hold said contact glass, an image sensor configured to read an image on an original conveyed to the image reading location, through said contact glass, a reference member whose image is readable by said image sensor, and a moving mechanism configured to move at least one of said image sensor and said reference member relatively so as to enable said image sensor to read alternatively the original conveyed to the image reading location and said reference member,   wherein said reference member comprises a white coating film formed on an original conveying path-side surface of said contact glass, and a protective member covering at least a portion of said white coating film, for protection of said white coating film.   
   
   
       7 . An image reading apparatus configured to read an image formed on an original, comprising:
 an image reading unit including a frame that has an opening formed in an original conveying path side thereof, and rotatably supports a pivot shaft of an image sensor housed in said frame, a contact glass disposed on the opening of said frame, configured to guide the original to an image reading location thereon, and a reference member disposed within said frame.   
   
   
       8 . An image reading unit provided in an image reading apparatus as claimed in  claim 7 . 
   
   
       9 . An image reading apparatus for reading an image formed on an original, while conveying the original, comprising:
 a contact glass configured to have an original conveying surface on which an original reading position and a reference member reading position exist, and guide the original on the original conveying surface;   an image sensor configured to be capable of moving a reading position thereof between a position opposed to the original reading position and a position opposed to the reference member reading position, and read the image formed on the original through said contact glass guided on the original conveying surface of said contact glass; and   a shading correction reference member as a white reference for said image sensor,   wherein said shading correction reference member comprises a white coating film formed on an original conveying path-side surface of said contact glass, and a protective member covering at least a portion of said white coating film, for protection of said white coating film.   
   
   
       10 . An image reading apparatus according to  claim 9 , wherein said protective member is a substantially white adhesive tape. 
   
   
       11 . An image reading apparatus according to  claim 9 , wherein said protective member is substantially white, and wherein said shading correction reference member has a transparent fixing member provided between said protective member and said white coating film, for fixing said protective member to a surface of said white coating film. 
   
   
       12 . An image reading apparatus according to  claim 9 , wherein said shading correction reference member has a substantially white fixing member provided between said protective member and said white coating film, for fixing said protective member to a surface of said white coating film. 
   
   
       13 . An image reading apparatus according to  claim 9 , wherein said shading correction reference member has a two-sided adhesive tape for fixing said protective member, in a manner opposed to said white coating film, to at least one of a portion of said white coating film and a portion of said contact glass other than a portion close to said reference member reading location. 
   
   
       14 . An image reading apparatus according to  claim 11 , wherein said fixing member is a two-sided adhesive tape. 
   
   
       15 . An image reading apparatus according to  claim 11 , wherein said fixing member is an adhesive. 
   
   
       16 . An image reading apparatus according to  claim 11 , wherein said protective member is a sheet form member. 
   
   
       17 . An image reading apparatus according to  claim 11 , wherein said protective member is a sheet metal member. 
   
   
       18 . A shading correction reference member disposed at a reference member reading location on a contact glass provided in an image reading apparatus, comprising:
 a white coating film formed on an original conveying path-side surface of the contact glass; and   a protective member covering at least a portion of said white coating film, for protection of said white coating film.