Konica Minolta Business Technologies, Inc.

Konica Minolta, Inc.

Wataru Onoda

Kanji Nakayama

Tomohisa Yoshida

Noboru Ito

Masayasu Haga

Narutaka Yoshida

Hiroaki Takada

Tomohiro Kato

Dai Suwama

Yoshiyuki Iguchi

A developing device having: a developing sleeve in which a magnetic member is inserted, transporting two-component developer to a developing area facing an image carrier; and a restriction member for restricting the amount of developer to be no greater than 250 g/m. The average of absolute values of magnetic flux density within a restriction area falls within a range of 40 mT to 70 mT under a condition that no developer exists within the restriction area. The restriction area extends along the outer circumferential surface between a closest point on the outer circumferential surface, which is closest to the restriction member, and a point 2 mm upstream from the closest point in a rotational direction of the developing sleeve, and has a height that is half a minimum distance between the closest point and the restriction member.

Developing device and image forming apparatus

A developing device having: a guide member creating a guide channel for guiding the developer being fed thereto while being supported on the developer support; and a regulating member regulating the amount of the developer that has passed through the guide channel, the guide member further creates a reflux channel in a gap from an inner surface of the housing, the reflux channel is connected to the guide channel via a communication channel such that the developer regulated by the regulating member returns toward an upstream end of the guide member, the upstream end of the guide member is disposed in a position opposed to the position where the magnetic flux density of the catch pole peaks, and the magnet assembly further includes a feeding pole that is disposed downstream of the catch pole and upstream of the developing pole, so as to be opposed to the guide channel.

Developing device and image forming apparatus including same

An image forming apparatus, wherein the packing density at a closest point where the first peripheral surface and the second peripheral surface are the closest to each other is within a range from 0.3 to 0.4; wherein a maximum magnetic flux density of a principal magnetic pole for generating the magnetic field for development is located in an upstream side from the closest point with respect to the specified direction and at a point where the packing density is equal to or greater than 0.2; and wherein a magnetic flux density of the principal magnetic pole at a point where the packing density is 0.2 in a downstream side from the closest point with respect to the specified direction is equal to or less than &#xbd; of a magnetic flux density of the principal magnetic pole at a point where the packing density is 0.2 in the upstream side.

Image forming apparatus

An image forming apparatus for forming a toner image on a print medium with a developer composed of toner and carriers, wherein when the first distance is longer than the second distance, an average gap between the first peripheral surface and a member that faces to the first peripheral surface in an area with a length of the first distance extending upstream from the closest point with respect to the specified direction is smaller than an average gap between the first peripheral surface and a member that faces to the first peripheral surface in an area with a length of the first distance extending downstream from the closest point with respect to the specified direction.

A two-component developing device using a developer containing toner and magnetic carrier particles. The developing device comprises a housing, a developing roller, a magnetic field generator mounted inside the developing roller, and a developer restricting member, and further comprises a developer guide member providing a developer guide path for guiding the developer to the developer amount restricting clearance, providing a developer circulation path for circulating the developer to an upstream end of the guide member, and providing a communication path for bringing the developer guide path into communication with the developer circulation path, an upstream end of the guide member being positioned above the position of a peak of magnetic flux density of the magnetic pole of the magnetic field generator which is closest to a low-magnetic force area downstream of the low-magnetic force area or positioned upstream of such a position and downstream of the low-magnetic force area. An image forming device in which such a two-component developing device is employed as at least one developing device.

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Toyokawa, Japan

Wataru Onoda