Ricoh Company, Ltd.

Ricoh Printing Systems, Ltd.

Kaoru Kataoka

Akio Tsujita

Hiroyuki Seki

Makoto Komatsu

Atsushi Mori

Yasuo Takuma

Shunichi Oohara

Katsuhiko Suzuki

Mikio Kamoshita

Masaru Kumagai

Tatsuya Kubo

An image forming apparatus includes a latent image carrier carrying a latent image, a developing device visualizing the latent image utilizing a two-component developer, a supply device supplying toner according to a change in toner density in the two-component developer inside the developing device, and a control device having an input side connected to a density sensor detecting a value of the toner density and an image information acquisition device acquiring information on an image formed on the latent image carrier, and an output side connected to a driving device driving the supply device. When the detected value is higher than a target value of the toner density stored by the control device, the control device performs control to stop the driving device or drive the driving device to supply toner in an amount less than a combined toner supply amount of first and second toner supply amounts.

Developing device and image forming apparatus

An image forming apparatus includes a controller, a database, an image carrier, a transfer unit, a fixing device including a temperature detector and a first drive device, a speed changer, and an electric-current detector. The controller calculates a toner adhesion amount of a recording medium, identifies a type of the recording medium, detects a temperature of the fixing device, determines a moisture content of the recording medium, calculates a reaction force of the recording medium, calculates a toner adhesion force, compares the reaction force and the toner adhesion force, determines a fixing nip angle, drives the first drive device to set the fixing device to the fixing nip angle, determines a target feed speed of the recording medium, and drives the speed changer to change a feed speed of the recording medium to match the target speed.

Image forming apparatus employing fixing device and control method therefor

An electrophotographic image forming apparatus is disclosed. The electrophotographic image forming apparatus includes a photoconductor body, a donor roller which develops an electrostatic latent image on the surface of the photoconductor body by using charged toners, and a development nip section formed between the photoconductor body and the donor roller by having a predetermined gap between the photoconductor body and the donor roller. A developing traveling-wave electrode for generating a traveling-wave electric field is disposed at a position facing the surface of the donor roller at an upstream side of the moving direction of the photoconductor body relative to the development nip section, and a removing traveling-wave electrode for generating a traveling-wave electric field is disposed at a position facing the surface of the donor roller at a downstream side of the moving direction of the photoconductor body relative to the development nip section.

Electrophotographic image forming apparatus

A developing unit includes a plurality of developing rolls over which a developer is conveyed and supplied onto an image carrier which is rotatably supported; and at least one pair of the developing rolls being adjacent to each other. In the pair of the developing rolls, one developing roll rotates in a direction opposite to a rotary direction of the image carrier, and the other developing roll rotates in the same direction of the rotary direction of the image carrier. A regulation member is interposed between the pair of the developing rolls. The regulation member regulates a conveyed amount of the developer. The regulation member is disposed to be opposed to a magnet which is provided within the two adjacent developing rolls. A polarity of the magnet in the pair of developing rolls opposed to each other is different from each other.

Developing unit and image forming apparatus

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.

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Kanagawa, Japan

Kaoru Kataoka