Developing device and process cartridge with predetermined magnetic force for an image forming apparatus

A process cartridge comprising a developing device for developing a latent image formed on an image carrier, said developing device comprising:

• a rotatable, nonmagnetic developer carrier;
• and
• means for generating a magnetic field in a developing zone where said developer carrier faces the image carrier, said magnetic field causing a developer deposited on said developer carrier to rise in the form of a magnet brush,
• wherein a first magnetic pole for development is located upstream of a closest position where said developer carrier and the image carrier are closest to each other in a direction of rotation, a second magnetic pole is located just downstream of the first magnetic pole and a radial flux density of said second magnetic pole is higher than a radial flux density of said first magnetic pole, and
• a magnetic force, as measured on a surface of said developer carrier, continuously increases from a position of the first magnetic pole toward a position where the magnet brush finally leaves the image carrier.

An image forming apparatus comprising a developing device for developing a latent image formed on an image carrier, said developing device comprising:

• a rotatable, nonmagnetic developer carrier;
• and
• means for generating a magnetic field in a developing zone where said developer carrier faces the image carrier, said magnetic field causing a developer deposited on said developer carrier to rise in the form of a magnet brush,
• wherein a first magnetic pole for development is located upstream of a closest position where said developer carrier and the image carrier are closest to each other in a direction of rotation, a second magnetic pole is located just downstream of the first magnetic pole and a radial flux density of said second magnetic pole is higher than a radial flux density of said first magnetic pole, and
• a magnetic force, as measured on a surface of said developer carrier, continuously increases from a position of the first magnetic pole toward a position where the magnet brush finally leaves the image carrier.

A developing device for developing a latent image formed on an image carrier, said developing device comprising:

• a rotatable, nonmagnetic developer carrier;
• and
• means for generating a magnetic field in a developing zone where said developer carrier faces the image carrier, said magnetic field causing a developer deposited on said developer carrier to rise in the form of a magnet brush,
• wherein a first magnetic pole for development is located upstream of a closest position where said developer carrier and the image carrier are closest to each other in a direction of rotation, a second stationary magnetic pole is fixedly located just downstream of the first magnetic pole, and
• a magnetic force, as measured on a surface of said developer carrier, continuously increases from a position of the first magnetic pole toward a position where the magnet brush finally leaves the image carrier.

A process cartridge comprising a developing device for developing a latent image formed on an image carrier, said developing device comprising:

• a rotatable, nonmagnetic developer carrier;
• and
• means for generating a magnetic field in a developing zone where said developer carrier faces the image carrier, said magnetic field causing a developer deposited on said developer carrier to rise in the form of a magnet brush,
• wherein a first magnetic pole for development is located upstream of a closest position where said developer carrier and the image carrier are closest to each other in a direction of rotation, a second stationary magnetic pole is fixedly located just downstream of the first magnetic pole, and
• a magnetic force, as measured on a surface of said developer carrier, continuously increases from a position of the first magnetic pole toward a position where the magnet brush finally leaves the image carrier.

An image forming apparatus comprising a developing device for developing a latent image formed on an image carrier, said developing device comprising:

• a rotatable, nonmagnetic developer carrier;
• and
• means for generating a magnetic field in a developing zone where said developer carrier faces the image carrier, said magnetic field causing a developer deposited on said developer carrier to rise in the form of a magnet brush,
• wherein a first magnetic pole for development is located upstream of a closest position where said developer carrier and the image carrier are closest to each other in a direction of rotation, a second stationary magnetic pole is fixedly located just downstream of the first magnetic pole, and
• a magnetic force, as measured on a surface of said developer carrier, continuously increases from a position of the first magnetic pole toward a position where the magnet brush finally leaves the image carrier.