Patent ID: 9341986
Filing Date: 2016-05-17
CPC Classification: G03G

Claim Text:
1. A developing device comprising: a developer carrier that includes a magnetic field generator housed in the developer carrier, and that rotates, with a developer containing toner and magnetic carriers and carried on a surface of the developer carrier with a magnetic force that is generated by the magnetic field generator, so as to convey the developer to a developing area where the developer is opposed to the surface of a latent image carrier; a developer control member that forms, between the developer control member and the surface of the developer carrier, a control gap through which the developer carried on the surface of the developer carrier passes and accordingly the amount of the developer to be conveyed to the developing area is controlled; and a developer supply conveyance path that is disposed adjacent to the surface of the developer carrier, in which the developer to be supplied onto the surface of the developer carrier is conveyed with a developer supply conveyance member along a direction of a rotation axis of the developer carrier, and into which the developer that is prevented by the developer control member from passing through the control gap is collected, wherein the magnetic field generator includes at least: a drawing-up magnetic pole that generates a drawing-up magnetic force for attracting the developer in the developer supply conveyance path toward the developer carrier over an upper end of a side wall on a side of the developer carrier in the developer supply conveyance path and for drawing up the developer to the surface of the developer carrier; and a control magnetic pole that generates a control magnetic force for causing carrier chains in the developer that is passing through the control gap, the drawing-up magnetic pole and the control magnetic pole are adjacent to each other in the direction in which the surface of the developer carrier moves and have polarities opposite to each other, a prevention member is provided that secures, between the prevention member and the upper end of the side wall, a supply path through which the developer in the developer supply conveyance path passes toward the developer carrier at least over an entire area along the direction of the rotation axis of the developer carrier in the developing area and that prevents the developer, which is prevented by the developer control member from passing through the control gap, from moving toward the surface of the developer carrier along lines of the control magnetic force, and the peak of magnetic flux density of the drawing-up magnetic pole in the normal direction is disposed below the lower end of the supply path.