Ricoh Company, Ltd.

Yoshiyuki Takano

Kyohta Koetsuka

Noriyuki Kamiya

Masayuki Ohsawa

Hiroya Abe

Takashi Innami

Mieko Terashima

Tsuyoshi Imamura

Tadaaki Hattori

Rei Suzuki

Masaki Watanabe

Shigeharu Nakamura

Yuji Suzuki

Yoshio Hattori

Hiroyuki Uenishi

Takamasa Ozeki

Sumio Kamoi

Katsumi Masuda

Toshio Kojima

Takumi Terasaka

Satoshi Terashima

Makoto Nakamura

Nobuyuki Taguchi

Takeroh Kurenuma

Akira Azami

Atsushi Ohta

Taisuke Tokuwaki

Takayuki Yoshii

Mieko Kakegawa

Kyoichi Ashikawa

Mieko Kakegawa/Terashima

A magnet roller includes a roller-shaped body constructed of a magnetic field generating material, a first support rod provided to a first axial end of the body; and a second support rod provided to a second axial end of the body. At least one of the first and second support rods is constructed of a nonmagnetic material and includes a projecting part projecting outside the body from an end face of the body and a buried part united to the projecting part and positioned inside the body. The buried part includes a reduced-area portion smaller than a base end of the projecting part adjacent to the buried part in cross-sectional area perpendicular to an axial direction of the first and second support rods.

Magnet roller, developer bearer, development device, process cartridge, and image forming apparatus

A develop roller includes a magnet roller, and a develop sleeve containing the magnet roller and comprising a plurality of depressions in an elliptic shape regularly arranged with an interval in a longitudinal direction on a surface onto which developer is attracted by a magnetic force of the magnet roller, wherein the depressions are arranged such that a longitudinal direction of the depressions is intersected with the longitudinal direction of the develop sleeve, and a downstream side of the depressions are formed to be deeper than an upstream side in a rotary direction of the develop sleeve.

Develop roller, develop unit, process cartridge, and image forming apparatus

A magnet roller includes a magnetic field generator being columnar, a support element being columnar, coaxially provided at both ends of the magnetic field generator, and whose diameter is smaller than that of the magnetic field generator, a level element extending along an axis of the magnetic field generator with a distance from the axis, the distance larger than the diameter of the support element, and a high magnetic power element being a main magnetic pole provided on the level element, extending long along the axis of the magnetic field generator.

Magnet roller, developer holder element, develop unit, process cartridge, and image forming apparatus

A magnetic particle carrying device includes a magnetic field generator and a hollow cylindrical structure. The magnetic field generator generates a magnetic field. The hollow cylindrical structure encases the magnetic field generator and attracts magnetic particles on an external surface of the hollow structure using the magnetic field. The external surface of the hollow cylindrical structure is provided with a plurality of elliptical depressions. The depressions include first type depressions and second type depressions. A long axis of a first type of elliptical depression is substantially extending in an axial direction of the hollow cylindrical structure, and a long axis of a second type of elliptical depression is substantially extending in a circumferential direction of the hollow cylindrical structure. The external surface of the hollow cylindrical structure has more elliptical depressions of the second type than elliptical depressions of the first type.

Magnetic particle carrying device, and developing unit, process cartridge, and image forming apparatus using the same, and surface treatment method of the same

A magnetic roller includes a solid-core roller having magnetic anisotropy in a direction orthogonal to a central axis thereof. The solid-core roller includes a body part, and shaft parts disposed on both ends of the body part, a concave groove provided in an outer circumference face of the body part to extend in an axial direction, and a magnetic block disposed in the concave groove, the magnetic block having a direction of magnetic anisotropy substantially orthogonal to a direction of the magnetic anisotropy of the magnetic roller.

Magnetic roller and manufacturing method thereof, developer carrier, development device, processing cartridge, and image forming apparatus

A developing unit includable in a process cartridge and in an image forming apparatus includes a developer bearing member including a magnetic field generator and a nonmagnetic hollow member, a developer container, an agitation/conveyance member, and a developer regulating member. The magnetic field generator has first and second magnetic poles to generate respective magnetic forces for removing the developer from the developer bearing member after the developer passes the development region. A developer-releasing region releases the developer from the developer bearing member using a release force. The developer is disposed higher than a surface of the developer in the developer storing chamber. A component of a magnetic flux density of the magnetic field generated by the magnetic field generator in a direction normal to the developer-releasing region is directed to a same direction as the first and second magnetic poles across the developer-releasing region without forming a local maximum point.

Developing unit, image forming apparatus incorporating same, and process cartridge including same

A development roller, including a development sleeve disposed near a photo conductive drum, a magnetic roller disposed in the development sleeve, and a supplying device configured to supply a developer including a toner and a magnetic carrier to the photo conductive drum uniformly, the development sleeve having an outer surface on which the developer including the toner and the magnetic carrier is adsorbed by a magnetic force of the magnetic roller.

Development roller including a development sleeve, surface treatment device that treats an outer surface of the development sleeve and wire member that roughens the outer surface of the development sleeve

A developing unit includable in a process cartridge and in an image forming apparatus includes a developer bearing member including a magnetic field generator and a nonmagnetic hollow member, a developer container, an agitation/conveyance member, a developer regulating member to regulate the thickness of a layer of the two-component developer. The magnetic field generator has first and second magnetic poles to generate respective magnetic forces for removing the developer from the developer bearing member after the developer passes the development region. The second magnetic pole generates a magnetic force to attract the developer to form a magnetic brush on the developer bearing member. The developer regulating member includes a magnetic member outwardly disposed on an exterior perimeter surface of the developer bearing member upstream from the developer regulating member, and one planar surface of the magnetic member faces the second magnetic pole across an effective development region.

Developer regulating member in a developing unit, process cartridge including same, and image forming apparatus incorporating same

An image forming device comprises a process cartridge. The process cartridge comprises a development roller. The development roller comprises a magnet roller and a developing sleeve. The magnet roller is fixed. The depressionseach having an oval shape are formed on the external surface of the developing sleeve. Both ends of the depressionswhich are adjacent with each other along the longitudinal direction of the developing sleeveare overlapped with each other and both ends of the depressionswhich are adjacent with each other along the circumferential direction of the developing sleeveare spaced with each other.

Development roller, development device, process cartridge and image forming device

A magnet roller includes a cylindrical roller body including a side surface in which a groove is formed, a magnet body which is disposed in the groove, and a magnetic metal member which is attached to a surface of the magnet body, which is remote from an opening of the groove.

Magnet roller and method for the same, magnetic particle-support member, development device, process cartridge, and image forming apparatus

A magnetic field generating member with high stiffness and small size, an image development device, a process cartridge and an image forming apparatus including the magnetic field generating member as well as a manufacturing method of the magnetic field generating member are provided where the magnetic field generating member includes a main body, a groove provided in the main body, an interposition member configured to be fitted in the groove of the main body and including a concave portion and a magnetic member as a long magnetic compact fixed into the concave portion of the interposition member.

Magnetic field generating member and manufacturing method thereof, magnetic particle support body, image development device, process cartridge and image forming apparatus

A developer carrier includes a magnetic field generating device provided with a plurality of magnetic poles including an agent separating pole and a scooping pole, and a cylindrical hollow body accommodating therein the magnetic field generating device and rotated around an axis of the cylindrical hollow body. A half-value width of a magnetic flux density at both end portions of at least one magnetic pole of the agent separating pole and the scooping pole is formed to be identical to or narrower than a half-value width of the magnetic flux density at a central portion of the one magnetic pole.

Developer carrier, development device, process cartridge, and image forming apparatus

A method of manufacturing a hollow body having an external surface randomly provided with a large number of depressions is provided. The method includes providing the large number of depressions on the external surface of the hollow body. A profile curve of the external surface in a circumferential direction is obtained while rotating the hollow body. A frequency analysis is performed on the obtained profile curve. A quality of the hollow body is judged by comparing a result of the frequency analysis with a predetermined judgment standard.

Method of manufacturing a hollow body used in an image forming apparatus

A magnetic roller includes a cylindrical magnetic field generation part (), a cylindrical support part () that contacts both of the edges of the magnetic field generation part (), further has a smaller diameter than the magnetic field generation part (), and which is installed upon a common axis thereof as an axis of the cylindrical support part (), and a depression part () that is installed upon an obverse surface of the cylindrical magnetic field generation part (), extends in a direction of the axis of the magnetic field generation part (), and wherein a lengthwise magnet formation is inserted. The cylindrical magnetic field generation part () is configured of a main body portion (), which is installed upon a central portion of the cylindrical magnetic field generation part (), and a reinforcing portion (), which is installed upon each of both ends, wherein the depression part () is installed across the main body portion () of the magnetic field generation part () overall, and the reinforcing portion () is installed between an end of the depression part () and an end of the support part.

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Hachioji, Japan

Yoshiyuki Takano