Electroconductive magnetic carrier, developer using the same and image formation method

A developer comprising

• (a) an electroconductive magnetic carrier comprising carrier particles with an average particle diameter of b 5 to 100 .mu.m, each of said carrier particles comprising
• (i) a basic particle which comprises a binder resin and discrete magnetic particles with an average particle diameter of 0.05 to 1.0 .mu.m dispersed in said binder resin, and
• (ii) electroconductive finely-divided particles with an average particle diameter of 0.5 .mu.m or less which are fixed on the surface of said basic particle;
• and
• (b) an electrically insulating toner.

An image formation method of forming a toner image particle to a light image on a photoconductor by use of (a) a photoconductor which comprises a light-transmitting support, and at least a light-transmitting electroconductive layer and a photoconductive layer which are successively overlaid on said light-transmitting support, (b) a developer comprising an electroconductive magnetic carrier comprising carrier particles with an average particle diameter of 5 to 100 .mu.m, each of said carrier particles comprising a basic particle which comprises a binder resin and discrete magnetic particles with an average particle diameter of 0.05 to 1.0 .mu.m dispersed in said binder resin, and electroconductive finely-divided particles with an average paricle diameter of 0.5 .mu.m or less which are fixed on the surface of said basic particle;

• and an electrically insulating toner, (c) a develoment means which is disposed on the side of said photoconductive layer of said photoconductor and supplies said developer onto the surface of said photoconductor, (d) a voltage application means for applying a voltage across said light-transmitting electronconductive layer of said photoconductor and said development means, and (e) an exposure means which is disposed on the side of said light-transmitting support of said photoconductor in such a configuration as to be directed toward said development means, comprising the steps of
• bringing said developer into contact with the surface of said photoconductor;
• and
• applying a light image to said photoconductive layer located near a position where said light-transmitting support and said development means are mutually directed, from the side of said light-transmitting support, under the application of a voltage across said light-transmitting electroconductive layer and said development means.