Magnetic roller, developer carrier, developing device, process cartridge, and image forming apparatus

A developer carrier, comprising:

• a magnetic roller including
• a cylindrical magnetic field generation part;
• a cylindrical support part configured to contact each of both ends of the cylindrical magnetic field generation part, and having a smaller diameter than the cylindrical magnetic field generation part, and to be installed upon a common axis thereof as an axis of the cylindrical support part;
• and
• a depression part, including a first depression part and a second depression part thereof, to be installed upon an obverse surface component of the cylindrical magnetic field generation part, to extend in a direction of the axis of the cylindrical magnetic field generation part, and wherein a lengthwise magnet formation is to be inserted;
• wherein the cylindrical magnetic field generation part includes a main body portion, which is installed upon a central portion of the cylindrical magnetic field generation part, and a reinforcing portion, which is installed upon each both ends of the cylindrical magnetic field generation part;
• wherein the first depression part is installed across the main body portion of the cylindrical magnetic field generation part overall;
• the reinforcing portion is installed between an end of the first depression part and an end of a support part thereof;
• wherein a triangular cross-section layer is installed upon the reinforcing portion thereof, the triangular cross-section layer having an incline configured to be installed from an edge of the reinforcing portion that contacts an edge of an obverse surface of a support part thereof, to a lower surface of both of an edge of the first depression part, wherein an angle that is formed by the incline thereof and a lower surface of the first depression part is presumed to be greater than 90 degrees and less than 180 degrees;
• and
• the second depression part thereof is installed upon the incline thereof;
• and
• a non-magnetic cylindrical body configured to be rotatably mounted upon an external circumference of the magnetic roller.

An image forming apparatus, comprising:

• a process cartridge including a developing device, the developing device including a developer carrier, the developer carrier including a magnetic roller and a non-magnetic cylindrical body configured to be rotatably mounted upon an external circumference of the magnetic roller, the magnetic roller including
• a cylindrical magnetic field generation part;
• a cylindrical support part configured to contact each of both ends of the cylindrical magnetic field generation part, and having a smaller diameter than the cylindrical magnetic field generation part, and to be installed upon a common axis thereof as an axis of the cylindrical support part;
• and
• a depression part, including a first depression part and a second depression part thereof, to be installed upon an obverse surface component of the cylindrical magnetic field generation part, to extend in a direction of the axis of the cylindrical magnetic field generation part, and wherein a lengthwise magnet formation is to be inserted;
• wherein the cylindrical magnetic field generation part includes a main body portion, which is installed upon a central portion of the cylindrical magnetic field generation part, and a reinforcing portion, which is installed upon each both ends of the cylindrical magnetic field generation part;
• wherein the first depression part is installed across the main body portion of the cylindrical magnetic field generation part overall;
• the reinforcing portion is installed between an end of the first depression part and an end of a support part thereof;
• wherein a triangular cross-section layer is installed upon the reinforcing portion thereof, the triangular cross-section layer having an incline configured to be installed from an edge of the reinforcing portion that contacts an edge of an obverse surface of a support part thereof, to a lower surface of both of an edge of the first depression part, wherein an angle that is formed by the incline thereof and a lower surface of the first depression part is presumed to be greater than 90 degrees and less than 180 degrees;
• and
• the second depression part thereof is installed upon the incline thereof.