Developing device, process cartridge, and image forming apparatus

A process cartridge which is detachably mountable to an electrophotographic image forming apparatus, the process cartridge comprising:

• an electrophotographic photosensitive member;
• a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive member;
• a magnet provided on an inner side of the developing roller and having a plurality of local maximum magnetic flux density positions in each of which a magnetic flux density is local maximum on a peripheral surface of the magnet;
• a developing container supporting the developing roller;
• a seal member provided at an end portion in an axial direction of the developing roller, for preventing a developer supplied to the developing roller from leaking out of the developing container in the axial direction of the developing roller;
• a developer regulating member for regulating an amount of developer on the peripheral surface of the developing roller, the developer regulating member having an elastic portion abutting the developing roller and a supporting portion formed of a metal material and supporting the elastic portion;
• and
• a scraping member abutting the developing roller at an end portion in the axial direction of the developing roller, for collecting the developer on the peripheral surface of the developing roller toward an inner side of the developing container in the axial direction,
• wherein, when the process cartridge is seen along the axial direction of the developing roller, the scraping member abuts the developing roller between a first position where the peripheral surface of the developing roller is crossed by a line which connects, of the plurality of local maximum magnetic flux density positions, the local maximum magnetic flux density position that is nearest to the supporting portion to the supporting portion, and a second position where the developing roller develops the electrostatic latent image.

An image forming apparatus, which is used to form an image on a recording medium, the image forming apparatus comprising:

• (i) an electrophotographic photosensitive member;
• (ii) a developing device comprising:
• a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive member;
• a magnet provided on an inner side of the developing roller and having a plurality of local maximum magnetic flux density positions in each of which a magnetic flux density is local maximum on a peripheral surface of the magnet;
• a developing container supporting the developing roller;
• a seal member provided at an end portion in an axial direction of the developing roller, for preventing a developer supplied to the developing roller from leaking out of the developing container in the axial direction of the developing roller;
• a developer regulating member for regulating an amount of developer on the peripheral surface of the developing roller, the developer regulating member having an elastic portion abutting the developing roller and a supporting portion formed of a metal material and supporting the elastic portion;
• and a scraping member abutting the developing roller at an end portion in the axial direction of the developing roller, for collecting the developer on the peripheral surface of the developing roller toward an inner side of the developing container in the axial direction, wherein, when the developing device is seen along the axial direction of the developing roller, the scraping member abuts the developing roller between a first position where the peripheral surface of the developing roller is crossed by a line which connects, of the plurality of local maximum magnetic flux density positions, the local maximum magnetic flux density position that is nearest to the supporting portion to the supporting portion, and a second position where the developing roller develops the electrostatic latent image;
• and
• (iii) conveying means for conveying the recording medium.

An image forming apparatus to which a process cartridge is detachably mountable for forming an image on a recording medium, the image forming apparatus comprising:

• (i) mounting means for detachably mounting the process cartridge, the process cartridge comprising:
• an electrophotographic photosensitive member;
• a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive member;
• a magnet provided on an inner side of the developing roller and having a plurality of local maximum magnetic flux density positions in each of which a magnetic flux density is local maximum on a peripheral surface of the magnet;
• a developing container supporting the developing roller;
• a seal member provided at an end portion in an axial direction of the developing roller, for preventing a developer supplied to the developing roller from leaking out of the developing container in the axial direction of the developing roller;
• a developer regulating member for regulating an amount of developer on the peripheral surface of the developing roller, the developer regulating member having an elastic portion abutting the developing roller and a supporting portion formed of a metal material and supporting the elastic portion;
• and a scraping member abutting the developing roller at an end portion in the axial direction of the developing roller, for collecting the developer on the peripheral surface of the developing roller toward an inner side of the developing container in the axial direction, wherein, when the process cartridge is seen along the axial direction of the developing roller, the scraping member abuts the developing roller between a first position where the peripheral surface of the developing roller is crossed by a line which connects, of the plurality of local maximum magnetic flux density positions, the local maximum magnetic flux density position that is nearest to the supporting portion to the supporting portion, and a second position where the developing roller develops the electrostatic latent image;
• and
• (ii) conveying means for conveying the recording medium.