Hitachi Koki Co., Ltd.

Ricoh Company, Ltd.

Hitachi, Ltd.

Ricoh Printing Systems, Ltd.

Yasuo Takuma

Hiroshi Kikuchi

Junichi Matsumoto

Tomoya Ohmura

Masanari Fujita

Natsumi Matsue

Teruaki Mitsuya

Masayasu Anzai

Masashi Yamamoto

Takao Umeda

Yoshitaka Fujinuma

Tatsuo Igawa

Hisao Okada

Tetsuya Nagata

Koji Kato

Shinya Kobayashi

Masahiko Saito

Takashi Suzuki

Hiroyuki Mabuchi

Nobuyoshi Hoshi

Takao Kumasaka

Masato Miwa

Katsuya Kawai

Akira Arimoto

Haruyuki Honda

Yoshito Tsunoda

Tatsuya Sugita

Kazuhiro Wakamatsu

Toru Miyasaka

Junichi Matsuno

Mamoru Okano

Tsuneaki Kawanishi

Shigeru Obata

Yasuyuki Tsuji

Natsumi Katoh

Masayuki Ainoya

Seiji Maruo

Yasuo Kikuchi

Yuzuru Simazaki

Masayoshi Ishii

Isamu Komatsu

Atsushi Onose

Tomio Sugaya

Tsutomu Nakagawa

Osamu Namikawa

Yuichiro Suzuki

Kazuo Uno

Tomonari Hokkyo

Masato Yamada

Kaoru Kataoka

Yosuke Saito

Yoshihiro Gunji

Hiroyoshi Matsumoto

Hisayoshi Kato

Hiroshi Hakuta

Masaki Tsuchiya

Nobuaki Fukasawa

Tomonari Hokkyou

A development device having a development portion with a developer spout, to develop a latent image formed on an image carrier with developer including toner and carrier particles. The development unit also includes a circulation unit to convey developer collected from the development portion to the developer spout, a developer container, provided in the circulation unit, to contain the developer at a position upstream from the development portion in a developer circular direction, the developer container having a cylindrical upper portion and a funnel-shaped lower portion continuous with the cylindrical upper portion through a joint so that a level of the developer contained in the developer container at rest is positioned near the joint between the cylindrical upper portion and the funnel-shaped lower portion. An agitator is provided inside the developer container, to agitate and mix the collected developer and fresh toner supplied to the developer container.

Development device and image forming apparatus incorporating same

In a disclosed developing device, a developing part includes a developer carrier for circulating a developer inside the developing part and for supplying the developer to an image carrier, a developer supply member for supplying the developer to the developer carrier, and a developer collection member for collecting the developer which is not used. A developer stirring part is arranged at a different position from a position of the developing part. A developer conveyance part carries the developer by an air conveyance in a developer conveyance path from the developer stirring part to the developing part. A developer detection part includes an opening which communicates between the developer supply member and the developer collection member, is arranged at a downstream side in a flow direction of the developer below and near the developer supply member, and detects whether the developer exists in a vicinity of the developer supply member.

Developing device and image forming apparatus

A development device includes a development portion, to develop a latent image formed on a latent image carrier with developer, disposed close to the latent image carrier; a developer agitation container to agitate the developer, provided separately from the development portion; a transport system connecting the development portion and the developer agitation container, through which the developer is transported from the developer agitation container to the development portion by air; and a developer retainer to temporarily retain the developer, disposed downstream from the transport system, to which the developer remaining in the transport system escapes.

A developing device in the embodiment includes: a developer carrier that carries a two-component developer, moves the surface, and supplies the toner to a latent image on a surface of a latent image carrier; a first conveying member that conveys the developer in a first conveying path; a second conveying member that conveys the developer in a second conveying path; and a developer passing unit that conveys upward the developer which has reached at a conveying-direction posterior end of the second conveying path and passes the developer to the first conveying path. The developer passing unit includes a plurality of pushing members that push up the developer. The developer can pass through from upper surfaces of the pushing members to lower surfaces of the pushing members.

A development device includes a developing section to visualize a latent image formed on a latent image carrier with developer including toner and carrier. The development device has a developer supply opening and a developer collection opening, a circulation unit to transport the developer collected from the developer collection opening of the developing section to the developer supply opening of the developing section and including a developer container to store the developer collected from the developing section disposed upstream from the development section in a direction in which the developer is circulated, and a developer cooler to cool the developer contained in the developer container.

Development device and image forming apparatus

A development device includes a development portion to develop a latent image; an agitation container to contain developer; a circulation system through which the developer is circulated between the development portion and the agitation container; a developer replenishing device to supply fresh developer to the agitation container; an agitator, provided inside the agitation container, to agitate and mix the developer collected from the development portion and the fresh developer from the developer replenishing device; and a developer escape chamber to discharge surplus developer in the agitation container, projecting from and continuous with the agitation container, the developer escape chamber defining a communication pathway in a side of the agitation container between the agitation container and the developer escape chamber through which the developer is moved between the agitation container and the developer escape chamber and having a discharge opening whose lower end is positioned higher than the communication pathway.

A developing device includes a developer supply part and a developer collecting part, wherein the developer supply part has a developer inlet port for introducing a developer supplied from a reservoir into the developer supply part and a developer extraction port provided on the side of the developer inlet port to remove a portion of the developer so as to define a quantity of the developer to be introduced in the developer supply part, and wherein the developer extraction port and the developer collecting part are connected to the reservoir.

According to one embodiment, an image forming apparatus includes a photoreceptor, a charging unit, an exposure unit, a developing unit, a transfer unit, a fixing unit, an environment detecting unit and a control unit. The charging unit includes a charger and a static eliminator. The charger contacts with a surface of the photoreceptor and charges the surface to a first voltage. The static eliminator contacts with the surface and discharges the surface to a second voltage. The environment detecting unit detects an environmental data. The control unit controls the first voltage based on the environmental data.

Image forming apparatus

A multicolor image forming apparatus includes: a photosensitive belt unit comprising; a driving roller; a driven roller; a photosensitive belt having a joint, and a charger charging a surface of the photosensitive belt; an exposure device forming an electrostatic latent image, based on image information of each color, on the photosensitive belt; a plurality of developing devices storing different color developers, and an intermediate transfer unit performing a first transfer by sequentially superimposing each color developer image formed on the photosensitive belt. The photosensitive belt is suspended around the driving roller and the driven roller and is rotated and driven by the driving roller. Each developing device contacts and retracts from the photosensitive belt so as to develop the electrostatic latent image into a visible image using each color developer. At least one developing device can retract from the photosensitive belt at a region other than an image region.

Multicolor image forming apparatus

An image-forming device including a plurality of supporting rollers, a photosensitive belt, a pressing roller, an intermediate roller, and a charging roller. The plurality of supporting rollers includes a preselected supporting roller. The photosensitive belt is circularly movably supported on the plurality of supporting rollers. The pressing roller is disposed to contact the photosensitive belt and to press the preselected supporting roller through the photosensitive belt. The intermediate roller is disposed away from the photosensitive belt and to contact the pressing roller. The intermediate roller is rotatable following rotation of the pressing roller. The charging roller is disposed to contact both the photosensitive belt and the intermediate roller and to press the preselected supporting roller through the photosensitive belt. The charging roller is rotatable following rotation of the intermediate roller to thereby charge the photosensitive belt.

Image-forming device comprising a contact charging unit

An image forming apparatus includes a photosensitive member being movable in a predetermined direction; a charging roller that charges a surface of the photosensitive member; and a static pre-eliminator that eliminates static electricity by irradiating the surface of the photosensitive member with light, the static pre-eliminator located on an upstream side of the charging roller in a direction of movement of the photosensitive member; wherein an arrangement and an exposure amount of the static pre-eliminator are set to satisfy E &#x2266;0.025&#xd7;exp(t/&#x3c4;) where &#x3c4;is a residual time constant of a photo carrier generated in the photosensitive member by the static pre-eliminator, t is a time period from a time when the photosensitive member passes through the static pre-eliminator to a time when the photosensitive member is charged by the charging roller, and E is a normalized exposure amount of the static pre-eliminator.

Image forming apparatus including static pre-eliminator

An image forming apparatus includes a toner concentration detector for detecting the toner concentration within a two-component developing unit, a toner supply unit for supplying a toner into the developing unit, a storage unit for sequentially holding and updating a history of a toner supply operation for a certain period of time, and a toner concentration control unit for determining the time of the toner supply operation by the toner supply unit, based on information stored in the storage unit and a difference between an output value of the toner concentration detector and a reference value, and maintaining the toner concentration constant.

Image forming apparatus with toner concentration controller

A metal holder has a V-shape in cross-section formed by two arm sections. PET sheets are attached to mutually opposed surfaces of respective arm sections, and part of each PET sheet extends toward the electrically-conductive roller beyond the arm section. Flocked sheets are attached to the surfaces of the respective PET sheets opposite the electrically-conductive roller, and contact the electrically-conductive roller.

In an image forming apparatus for charging a photosensitive body, changing the light exposure amount in at least three levels at exposure to light, thereby forming an electrostatic image made up of a high-potential part, a low-potential part, and an intermediate-potential part therebetween on the photosensitive body, and normally developing and inversely developing the electrostatic image using toners different in charge polarity for forming two types of toner images on the photosensitive body, a first developer used with a first toner image developing unit has electric resistance changed within 10% in the change range of applied voltage to the developer as the difference between a surface potential of the photosensitive body and a developing bias voltage.

Image forming electrophotography apparatus and magnetic developing unit

In a developing system containing a combination of forward-rotating and a backward-rotating developing rollers, a steady quantity of developing agent should be supplied to the developing rollers for high-quality printed images. This requirement can be satisfied by placing a doctor blade between an intersection point, where a line connecting the central axis of one of the developing rollers and its polarity reversing position meets a line connecting the central axis of the other of the developing rollers and its polarity reversing position, and the developing roller pair. Further, the doctor blade should be located on the upstream side of the developing agent flow relative to the central axes of the backward-rotating developing roller and the forward rotating developing roller with its rightmost side (upstream side) in parallel with the line connecting the central axes of the developing rollers, and the doctor gap (on the side of the developing roller to which the developing agent is supplied) should be greater than a minimum gap (doctor gap) between one end of the doctor blade and the surface of the developing roller to which the developing agent is first supplied.

Developing system having a plurality of developing rollers with opposing magnets of same polarity

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Kanagawa, Japan

Yasuo Takuma