| 摘要 |
PURPOSE:To enable development with good image quality by providing an electric resistance layer via an electrical insulating layer to a sleeve surface and providing a power feed part to at least one end of the electric resistance layer thereby forming a magnet roll in such a manner that the roll can be electrically heated. CONSTITUTION:The electric resistance layer 5 consisting of a mixture composed of fine particles of insulating ceramics such as Al2O3 and conductive material having high electrical resistivity such as Ni-Cr is provided on the outside of the electrical insulating layer 4 formed on the surface of the sleeve. Leads and other power feed parts consisting of a conductive material are provided to both ends in the axial direction of the electric resistance layer to form the sleeve in such a manner that the sleeve can be energized. While the electric resistance layer 5 is kept electrically heated, the temp. of a developer is maintained constant and development is executed by controlling the temp. to; for example, <=30 deg.C+ or -5 deg.C. The fluctuation in the substantial moisture in the developer is then decreased and even if the humidity changes in a 15-80% R.H. range, the electric charge quantity of a toner is kept at 18+ or -2muc/g. The good image is thereby obtd. |
