Patent ID: 8903266

Claim:
A developing device comprising: a housing; a developer supporting rotator disposed inside the housing, including, a first rotating sleeve configured to support a two-component developer including at least a carrier and toner, the first rotating sleeve extending in a longitudinal direction to form a face on which a magnetic brush is formed by the carrier included in the two-component developer, and a plurality of developer supporting side magnetic members that is disposed inside the first rotating sleeve and extends in the longitudinal direction; a toner supporting rotator disposed inside the housing including, a second rotating sleeve arranged opposite to the developer supporting rotator and extending in the longitudinal direction to form a face, on which a toner supplied from the developer supporting rotator is supported to form a toner layer through the magnetic brush, and a toner supporting side magnetic member that is disposed inside the second rotating sleeve and extends in the longitudinal direction; and a voltage application unit configured to apply a developing bias voltage between the toner supporting rotator and an image carrier, such that the toner supported by the toner supporting rotator flies to an electrostatic latent image on a surface of the image carrier to cause the electrostatic latent image to be developed into a toner image, wherein a longitudinal end portion of each of the pulurality of developer supporting side magnetic members is positioned more longitudinal outside than a longitudinal end portion of the toner supporting side magnetic member, a magnetic force generated in a vicinity of both longitudinal end portions is greater than a magnetic force generated at a longitudinally inner portion, with respect to an opposing magnetic member facing the toner supporting side magnetic member and a downstream magnetic member disposed more downstream in a rotational direction than the opposing magnetic member, among the plurality of developer supporting side magnetic members, the housing includes a sealing portion that projects from a position of the housing facing a longitudinal end face of the developer supporting rotator toward the longitudinal end face, such that the toner in a space between the longitudinal end face and an inner face of the housing is prevented from scattering outside the space, and the housing includes a concave portion that is positioned more longitudinally inside than the sealing portion and is configured to more recede in a direction away from a surface of the developer supporting rotator than the inner face of the housing that is located more longitudinally inside than the concave portion.