Developing apparatus, process cartridge, and image-forming apparatus

A process cartridge detachably mountable in an image-forming apparatus configured to form an image on a recording medium, the process cartridge comprising:

• a rotatable image-bearing member;
• a developer;
• and
• a developing roller configured to supply the developer to the image-bearing member,
• wherein the image-bearing member has a volume resistivity of 1014 ohm·cm or less,
• the developer satisfies the following conditions:
• in a state where a potential difference is formed between a surface of the rotatable developing roller and a developing blade in contact with the surface of the developing roller outside the image-forming apparatus, each of the developing roller and the developing blade has a resistance value of 1.0×104 ohms or less, and
• i) a first resistance value ranges from 1.0×105 ohms to 1.0×108 ohms as measured in a state where the developing roller is stopped and in a state where the developer is located between the developing roller and the developing blade, and
• ii) a second resistance value ranges from 1.0×105 ohms to 1.0×108 ohms and is 40% or more with respect to the first resistance value, as measured in a state where the developing roller is rotated at 200 mm/s with respect to the developing blade and in a state where the developer is located between the developing roller and the developing blade.

An image-forming apparatus comprising:

• a rotatable image-bearing member;
• a developer;
• and
• a developing roller configured to supply the developer to the image-bearing member,
• wherein the image-bearing member has a volume resistivity of 1014 ohm·cm or less,
• the developer satisfies the following conditions:
• in a state where a potential difference is formed between a surface of the rotatable developing roller and a developing blade in contact with the surface of the developing roller outside the image-forming apparatus, each of the developing roller and the developing blade has a resistance value of 1.0×104 ohms or less, and
• i) a first resistance value ranges from 1.0×105 ohms to 1.0×108 ohms as measured in a state where the developing roller is stopped and in a state where the developer is located between the developing roller and the developing blade, and
• ii) a second resistance value is in the range of the first resistance value ranges from 1.0×105 ohms to 1.0×108 ohms and is 40% or more with respect to the first resistance value, as measured in a state where the developing roller is rotated at 200 mm/s with respect to the developing blade and in a state where the developer is located between the developing roller and the developing blade.

An image-forming apparatus comprising:

• a rotatable image-bearing member including a base material and a surface layer on a surface thereof;
• a charging roller configured to charge a surface of the image-bearing member;
• a developing roller configured to supply the surface of the image-bearing member with the developer to be charged to a normal polarity;
• a charging voltage application portion configured to apply a charging voltage to the charging roller;
• a development voltage application portion configured to apply a development voltage to the developing roller;
• and
• a controller configured to control the charging voltage application portion and the development voltage application portion,
• wherein the controller is configured to form a potential difference between the image-bearing member and the developing roller so as to generate an electrostatic force that moves the developer charged to the normal polarity from the image-bearing member to the developing roller, and
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• are satisfied, wherein ρp denotes a volume resistivity of the surface layer of the image-bearing member, and ρd denotes a volume resistivity of the developing roller.