PROBLEM TO BE SOLVED: To form a uniform and precise image while developer is sufficiently carried by providing the surface of a developer carrier with many spherical recessed parts and specifying relation between the average diameter of the recessed part and the average grain size of the developer. SOLUTION: The developer carrier 9 is formed of a metal or resin and the surface thereof is roughened. The many spherical recessed parts of the surface of the carrier 9 are formed by using blast processing, etching processing or the like. It is preferable that the relation between the average diameter L of the spherical recessed part and the average grain size (d) of the developer 8 is d/4<=L<=8d. When the diameter L of the spherical recessed part becomes larger than 8d, the carrying quantity of the developer 8 is reduced and the desired carrying quantity is hardly obtained. Besides, fine density irregularity is caused according to the cycle of ruggedness. When the diameter L of the spherical recessed part becomes smaller than d/4, the carrying quantity of the developer 8 is increased but the electrifying quantity thereof is reduced. This is because the contact chance of the developer 8 with the carrier 9 or a regulation member 10 is reduced when the carrying quantity thereof is increased.
【課題】 画像が十分な濃度を確保しながら、現像剤に 十分に電荷を付与できるため微小ドットの再現性が優 れ、かつ現像剤担持体上の現像剤の入れ換えを十分に行 なうことにより現像履歴を発生せずに高画質な画像が形 成でき、さらに長期にわたり現像剤担持体への固着を発 生せず良好な画像を形成をする。
【解決手段】 現像剤担持体の表面は、球状の凹部が多 数存在しており、球状凹部の径Ｌと現像剤粒径ｄとの関 係はｄ／４≦ｒ≦８ｄを満たすことを特徴とする現像装 置。