| 摘要 |
A development roller has a core shaft and an external composite layer provided around the core shaft, the external composite layer including an elastic layer and a surface layer which are successively overlaid on the core shaft in that order, the development roller having a volume resistivity of 1.5x104 OMEGA.cm or less and an electrostatic capacity of 1.5x10-4 F/m2 or more. A developer unit is provided with the above-mentioned development roller which is disposed so as to have a toner deposited on an image portion formed on a surface of a photoconductor, a toner supply roller which is disposed opposite to the development roller and is capable of forming therearound a magnetic brush of the toner and a carrier, and brings the magnetic brush into contact with the development roller to supply the toner to the development roller, and a doctor blade disposed in contact with the surface of the toner supply roller to regulate the thickness of a layer of the toner.
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