Cylindrical developer carrier and production method thereof

Abstract

A cylindrical developer carrier capable of fully charging a toner compound on a developing sleeve via frictional force even after being used repeatedly. The cylindrical developer carrier includes an electrically conductive substrate having an evenly roughened surface, and an alumite layer formed on the roughened surface, wherein the alumite layer has a uniform distribution of minute holes that reach the substrate surface. A method for manufacturing the cylindrical developer carrier includes roughening the electrically conductive substrate surface by blasting it with spherical fine particles, forming the alumite layer on the roughened surface by an anodizing method, and blasting the surface of the alumite-layer with amorphous fine particles that a diameter greater than that of the spherical fine particles.

1 - 12 . (canceled)  
   
   
       13 . A cylindrical developer carrier comprising 
 an electrically conductive substrate having an evenly roughened surface; and    an alumite layer formed on said surface, wherein said alumite layer has a uniform distribution of minute holes respectively reaching said substrate surface.    
   
   
       14 . A cylindrical developer carrier according to  claim 13 , wherein said electrically conductive substrate is formed primarily of an aluminum-group metallic material.  
   
   
       15 . A cylindrical developer carrier according to  claim 13 , wherein said alumite layer comprises an alumite layer formed by an anodizing method.  
   
   
       16 . A cylindrical developer carrier according to  claim 15 , further comprising nickel acetate sealing said alumite layer.  
   
   
       17 . A cylindrical developer carrier according to  claim 13 , further comprising nickel acetate sealing said alumite layer.  
   
   
       18 . A cylindrical developer carrier according to  claim 17 , wherein said alumite layer has a thickness in the range of 2 μm to 5 μm.  
   
   
       19 . A cylindrical developer carrier according to  claim 13 , wherein said alumite layer has a thickness in the range of 2 μm to 5 μm.  
   
   
       20 . A cylindrical developer carrier according to  claim 19 , wherein said minute holes, as a whole, account for 10% to 50% of the total area of the alumite layer.  
   
   
       21 . A cylindrical developer carrier according to  claim 13 , wherein said minute holes, as a whole, account for 10% to 50% of the total area of the alumite layer.  
   
   
       22 . A method for manufacturing a cylindrical developer carrier comprising the steps of: 
 roughening an electrically conductive substrate surface by blasting spherical fine particles onto the substrate surface;    forming an alumite layer on the roughened surface by an anodizing method; and    blasting the surface of the alumite-layer with amorphous fine particles each having a diameter greater than that of the spherical fine particles.    
   
   
       23 . A method for manufacturing a cylindrical developer carrier according to  claim 22 , wherein 
 the blasting the spherical fine particles includes blasting the electrically conductive substrate surface with glass beads, and    the blasting the surface of the alumite layer with amorphous fine particles includes blasting the alumite layer surface with amorphous fine particles formed primarily of aluminum oxide, each of the amorphous fine particles having a diameter greater than that of the spherical fine particles.    
   
   
       24 . A method for manufacturing a cylindrical developer carrier according to  claim 23 , wherein 
 the step of blasting said electrically conductive substrate surface with spherical fine particles includes a step of blasting the substrate surface with spherical fine particles consisting solely of glass beads, so as to form a number of projections and recesses each having a mean surface roughness rated at Ra=0.8 μm to 1.5 μm, and    the blasting the surface of the alumite layer with amorphous fine particles includes blasting the alumite layer surface with amorphous fine particles formed primarily of aluminum oxide, each of the amorphous fine particles having a diameter greater than that of the spherical fine particles.