Ricoh Company, Ltd.

Kentaro Mikuniya

Junichi Matsumoto

Yutaka Takahashi

Kiyonori Tsuda

Keinosuke Kondoh

Toshio Koike

Nobuo Takami

Yasunobu Shimizu

Masaaki Yamada

Hideki Kosugi

Emiko Shiraishi

Makoto Yasuda

Nobuo Kuwabara

Akira Fujimori

Teppei Kikuchi

Akira Azami

Tetsuya Muto

Yoshiko Ogawa

Akihiro Kawakami

Mutsuki Morinaga

Yoshiharu Kishi

Yuichi Aizawa

Kazuhiro Aso

Yu Takahashi

A developing device includes a developer bearer to carry, by rotation, developer including toner and magnetic carrier to a developing range facing a latent image bearer; a casing including a developer container and an opening to expose a part of the developer bearer disposed in the casing; an opposing face of the casing including a conductive material and opposing to a surface of the developer bearer downstream from the developing range in a direction of rotation of the developer bearer; a developing bias source to apply a developing bias to the developer bearer; and an insulation layer disposed on the opposing face of the casing. The opposing face is disposed across, from the developer bearer, a casing gap sized to allow the developer borne on the developer bearer to contact the opposing face.

Developing device, and image forming apparatus and process cartridge incorporating same

A developing device includes: a developer bearer configured to bear developer thereon; a developer conveyance path for conveying developer to be fed to the developer bearer; a developer conveying member configured to convey the developer in the developer conveyance path; a developer discharge port disposed in the developer conveyance path to discharge developer from the developer conveyance path by overflow; and a contact member configured to be brought into contact with the developer conveyed toward the developer discharge port in the developer conveyance path, the developer conveyance path being configured to receive externally-supplied developer therein, the contact member being configured to repeat a sequence of movements including being elastically deformed by being brought into contact with the developer conveying member being driven and thereafter being elastically restored by being brought out of contact with the developer conveying member.

Developing device and image forming apparatus including a contact member which is elastically deformed

An image forming apparatus includes a developer conveyance device to transport developer, using a positive-displacement pump to alternately generate positive pressure and negative pressure by changing a volume of an internal space thereof, a destination developer container to which the developer conveyance device transports developer, a sensor provided to the destination developer container, to detect developer in the destination developer container, and a controller to control the positive-displacement pump according to a detection result generated by the sensor. The controller disabled detection of developer by the sensor in a non-detection period that starts from a stop of the positive-displacement pump.

Developer pump with restricted detection time and image forming device

A developing device includes a developer bearer to carry, by rotation, developer including toner and magnetic carrier to a development range facing a latent image bearer to bear a latent image. The developer bearer includes a magnetic field generator having multiple magnetic poles and a cylindrical developing sleeve to rotate and bear developer on an outer circumferential surface thereof with magnetic force of the magnetic field generator disposed inside the developing sleeve. The developing sleeve receives development voltage including an AC component having a frequency of 2.0 kHz or lower, and a duty ratio of a component having a polarity opposite a toner normal charge polarity of the AC component is within a range from 4% to 20%.

Developing device and image forming apparatus and process cartridge incorporating same

An image forming apparatus includes a developing device; a developer conveyance device including a developer container, a developer reservoir to receive developer discharged from the developer container, and a positive-displacement pump to discharge, from the developer reservoir, developer supplied to the developing device by alternately generating positive pressure and negative pressure due to volume changes; and a controller to control driving of the positive-displacement pump. When the controller recognizes a developer end state of the developer container, the controller lowers a developer conveyance capability of the positive-displacement pump from a setting used before the developer end state is recognized.

Developer conveyance device, image forming apparatus, and developer conveyance method

A developer conveyance device includes a developer reservoir for containing developer, and a positive-displacement pump to alternately generate positive pressure and negative pressure by varying a volume of space therein to transport developer from the developer reservoir to a destination. When Qp represents a volume of developer moved by a single pumping action of the pump, calculated by multiplying a maximum flow amount of the pump per unit time by an operation time of the pump; Qd represents a volume of developer contained in the developer reservoir; and Qe represents a volume of developer present in a virtual columnar space defined by vertically raising the developer outlet to a level of developer contained in the developer reservoir, either Qp&#x3e;Qd or Qp&#x3e;Qe is satisfied.

Developer conveyance device and image forming apparatus having a pump to move the developer in a relationship with the developer contained in a reservoir

A developer replenishing device includes a container mount to hold a developer container to contain developer used in image formation, an installation completion detector to detect completion of installation of the developer container in the container mount, a replaceable containing portion to contain developer, a conveyance channel to which the containing portion is removably connected and through which developer is transported from the developer container held in the container mount to the containing portion, and a conveyance pump to transport developer from the developer container through the conveyance channel to the containing portion. In a state in which the developer container is not held in the container mount according to a detection result by the installation completion detector, the conveyance pump transports developer from the conveyance channel to the containing portion.

Developer replenishing device to transport developer from developer container, image forming apparatus including same, and conveyance device to transport powder or fluid from container

A developing device includes a developer bearer to carry, by rotation, developer including toner and magnetic carrier to a development range facing a latent image bearer, and the developer bearer includes a magnetic field generator having multiple magnetic poles and a cylindrical developing sleeve to rotate and bear developer on an outer circumferential face thereof with magnetic force of the magnetic field generator provided inside the developing sleeve. The developing sleeve receives developing bias voltage including an AC component, and includes a base to maintain a cylindrical shape of the developing sleeve and a low friction surface layer including a material lower in friction coefficient with toner than a material of the base.

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Tokyo, Japan

Kentaro Mikuniya