Developing device
AssigneeCanon Kabushiki Kaisha
InventorsTomoyuki Sakamaki, Yuta Okuyama
Life of this patent
Estimating the term…
Abstract
A developing device includes a rotatable developing sleeve to carry and feed a developer including toner and a carrier toward a developing region, and a magnetic field generating portion provided inside the developing sleeve and having a developing magnetic pole for forming the developing region. The developing magnetic pole is disposed opposite to a closest position of the image bearing member to the developing sleeve. A ratio of an 80%-value-width of magnetic flux density of the developing magnetic pole with respect to a normal direction of the developing sleeve to a half peak width of the magnetic flux density of the developing magnetic pole with respect to the normal direction is 0.65 or more.
Claims11
A developing device comprising:
- a rotatable developing sleeve configured to carry and feed a developer including toner and a carrier toward a developing region where an electrostatic latent image formed on an image bearing member is developed with the developer;
- and
- a magnetic field generating portion provided inside said developing sleeve and having a developing magnetic pole, the developing magnetic pole being disposed opposite to a closest position of said image bearing member to said developing sleeve,
- wherein a ratio of an 80%-value-width of magnetic flux density of the developing magnetic pole with respect to a normal direction of said developing sleeve to a half peak width of the magnetic flux density of the developing magnetic pole with respect to the normal direction is 0.65 or more,
- wherein a magnetic force of the developing magnetic pole in the normal direction of said developing sleeve proximate to an upstream end portion of the developing region with respect to the rotational direction of said developing sleeve is larger than a magnetic force of the developing magnetic pole in the normal direction of said developing sleeve at a center portion of the developing region with respect to the rotational direction of said developing sleeve, with a peak position of the magnetic force of the developing magnetic pole in the normal direction of said developing sleeve proximate to the upstream end portion of the developing region with respect to the rotational direction of said developing sleeve being positioned outside of the developing region with respect to the rotational direction of said developing sleeve, and
- wherein a magnetic force of the developing magnetic pole in the normal direction of said developing sleeve proximate to a downstream end portion of the developing region with respect to the rotational direction of said developing sleeve is larger than the magnetic force of the developing magnetic pole in the normal direction of said developing sleeve at the center portion of the developing region with respect to the rotational direction of said developing sleeve, and
- a peak position of the magnetic force of the developing magnetic pole in the normal direction of said developing sleeve proximate to the downstream end portion of the developing region with respect to the rotational direction of said developing sleeve being positioned outside of the developing region with respect to the rotational direction of said developing sleeve.
Dependencies are inferred from the claim text.