| 摘要 |
PURPOSE: To well electrostatically attract a developer on a photoreceptor and to improve image quality by providing the above device with a developing tank formed with ruggedness to accelerate the triboelectrification of the developer on at least the inside surface facing a developer supplying roller. CONSTITUTION: A cartridge body 21 of a developing cartridge 20 of a laser beam printer is provided with a developing roller 22, a toner supply roller 23 as the developer supplying roller, a toner agitating roller 26 as a developer agitating roller, etc., in the developing tank 49. The ruggedness of a ten point average roughness Rz of about 10μm is formed on the inside wall surface 21a of the toner supplying roller 23. This Rz is 1/2×(toner average grain size) <=Rz<=10×(toner average grain size) if its adequate range is expressed by a relation with the toner grain sizes. Namely, the toners 24 are uniformly electrostatically charged and the stable images free from fogging are provided by finishing the inside wall surface 21a facing the roller ruggeder than by finishing this surface as a mirror finished surface. |
