Patent ID: 11874615
Assignee: KYOCERA DOCUMENT SOLUTIONS INC.
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A developing device, comprising:
a developing container that includes a plurality of conveyance chambers including a first conveyance chamber and a second conveyance chamber that are arranged mutually side by side and contains a two-component developer including a magnetic carrier and a toner;
a first stirring conveyance member that conveys, while stirring, the developer present in the first conveyance chamber in a first direction;
a second stirring conveyance member that conveys, while stirring, the developer present in the second conveyance chamber in a second direction opposite to the direction of conveyance by the first stirring conveyance member;
a developer carrying member that is rotatably supported to the developing container and carries, on an outer circumferential surface thereof, the developer present in the second conveyance chamber; and
a regulation member that is arranged to be opposed at a prescribed distance to the developer carrying member,
the developing device being configured to develop an electrostatic latent image formed on a surface of an image carrying member into a toner image,
wherein
the developer carrying member includes:
a developing sleeve that is rotatable, carries the developer, and has a surface on which a magnetic brush is formed; and
a magnet that is unrotatably secured in the developing sleeve and has a plurality of magnetic poles circumferentially arranged at prescribed intervals, which includes a regulation pole that is arranged at a position opposed to the regulation member and a main pole that is arranged on a downstream side of the regulation pole with respect to a rotation direction of the developing sleeve,

in the magnet, the regulation pole and a pumping pole that pumps the developer supplied from the second stirring conveyance member to the developer carrying member are constituted of a single magnetic pole, and the regulation pole has a region extending over 10° or more in which a maximum value of a vertical magnetic force is not more than 65 [mT] and a vertical magnetic force gradient is not more than 0.3 [mT/° ], and
a peak position of the vertical magnetic force gradient of the regulation pole is arranged at a position opposed to the second stirring conveyance member, and when a value of the vertical magnetic force gradient at the peak position of the vertical magnetic force gradient and a value of the vertical magnetic force at the peak position of the vertical magnetic force gradient are indicated as A [mT/° ] and K [mT], respectively, A≥2.8 and A×K≥62.5 are satisfied.