Image reading apparatus

Abstract

An image reading unit according to the present invention includes a lamp to incorporate a change in temperature conditions to the emitting light amount, the lamp capable of illuminating an reading object with a light of a predetermined intensity, an image signal generation unit which generates an image signal corresponding to the reflected light generated when a reading object is illuminated, and a cooling unit which cools a predetermined range of the lamp, so that the intensity change in the light radiated from the lamp of the illumination unit, in the length direction of the illumination unit can be suppressed.

1 . An image reading apparatus comprising: 
 an illumination unit including a lamp to incorporate a change in temperature conditions to the emitting light amount, the lamp extending in a predetermined direction and having a predetermined length, the lamp illuminating a reading object with a light of a predetermined intensity;    an image signal generation unit which generates an image signal corresponding to a reflected light based on the reflected light generated when the reading object is illuminated; and    a light intensity setting unit which sets a variation in the intensity of the light radiated from the illumination unit within a predetermined range in a length direction of the illumination unit.    
   
   
       2 . The image reading apparatus according to  claim 1 , wherein the light intensity setting unit maintains the temperature distribution in the length direction of the lamp of the illumination unit at a predetermined condition.  
   
   
       3 . The image reading apparatus according to  claim 2 , wherein the light intensity setting unit includes at least two fans, the fans provided at the positions satisfying the predetermined conditions concerning the length direction of the illumination unit.  
   
   
       4 . The image reading apparatus according to  claim 3 , wherein each of the fans can be changed independently in the distance to the lamp and/or the number of revolution.  
   
   
       5 . The image reading apparatus according to  claim 3 , further comprising an uniformalizing member which prevents the wind generated by the fan from applying directly to the lamp of the illumination unit.  
   
   
       6 . The image reading apparatus according to  claim 5 , wherein the uniformalizing member is made of metal with high thermal conductivity.  
   
   
       7 . A method for controlling a variation of light intensity of an illumination lamp in a longitudinal direction comprising: 
 detecting a variety of light intensity of the illumination lamp in the longitudinal direction based on a white reference marker which is outputted from a CCD sensor and provide a reference for shading; and    cooling the illumination lamp by at least two fans provided at positions separated in the longitudinal direction with variable amounts of cooling wind to set the output signal outputted from the CCD sensor and the variation of light intensity of the illumination lamp in the longitudinal direction within a predetermined range.    
   
   
       8 . The method according to  claim 7 , wherein the amount of cooling wind provided by each of the fans is controlled by the number of rotations of the fan.  
   
   
       9 . The method according to  claim 7 , wherein the amount of cooling wind provided by each of the fans is determined based on a distance between the fan and the illumination lamp.  
   
   
       10 . An image reading apparatus comprising: 
 an illumination unit including a lamp to incorporate a change in temperature conditions to the emitting light amount, the lamp extending in a predetermined direction and having a predetermined length, the lamp illuminating a reading object with a light of a predetermined intensity;    an image signal generation unit which generates an image signal corresponding to a reflected light based on the reflected light generated when the reading object is illuminated; and    a light intensity setting unit which includes at least two fans and sets a variation in the intensity of the light radiated from the illumination unit within a predetermined range in a longitudinal direction of the illumination unit in accordance with a temperature distribution in the longitudinal direction of the lamp.