Konica Minolta Business Technologies, Inc.

Tomoyuki Imura

Kazuhiro Saito

Takuya Okada

Chikara Tsutsui

Tomohiro Kato

Takayuki Takai

Takuya Sasaki

Junichi Hashimoto

Takanobu Yamada

Junji Murauchi

Hiroshi Mizuno

Naotoshi Kawai

Megumi Minami

Hiromasa Ueno

Eri Kusano

Kyoichi Yoshizawa

A first screen group and a second screen group are stored in an image forming apparatus. In the first screen group, the first region expands with increasing gradation value based on a first rule. In the second screen group, the first region expands with increasing gradation value based on an independent second rule different from the first rule. A screen selector relocates a first portion and a second portion such that the first portion and the second portion are joined by a second region that is not a toner adhesion control target, when the first portion and the second portion are adjacent as a result of the selection of the screen in each unit region of the input image. The first portion includes the screen included in the first screen group, and the second portion includes the screen included in the second screen group.

Image forming apparatus in which intermediate gradation reproducibility is enhanced

A developing device is provided with a developer transporting member for transporting a developer containing a toner and a carrier; a toner transporting member opposite to the developer transporting member and opposite to an electrostatic latent image carrying member; a first electric field forming device, which is composed of a power source for the developer transporting member and a power source for the toner transporting member, for shifting the toner in the developer held onto the developer transporting member to the toner transporting member; and a second electric field forming device for shifting the toner held onto the toner transporting member to an electrostatic latent image on the carrying member. Operation of the first electric field forming device is controlled based on an electric current flowing in the developer transporting member power source, which is detected by a detecting block.

Developing device, and controlling method thereof

A developing device is provided with a first transporting member for transporting a developer containing a toner and a carrier; a second transporting member opposite to the first transporting member to interpose a first spatial region therebetween and opposite to an electrostatic latent image carrying member to interpose a second spatial region therebetween; a first electric field forming device, composed of first and second power sources, for shifting the toner in the developer held onto the first transporting member to the second transporting member; and a second electric field forming device, composed of the second power source, for shifting the toner held onto the second transporting member to an electrostatic latent image on the carrying member. The operation of the second electric field forming device is controlled based on electric currents flowing in the first and second power sources, which are detected by first and second detecting blocks, respectively.

The present invention provides a developing device and an image forming apparatus capable of preventing a developer from being discharged excessively using simple configurations in the case that a trickle developing device that uses a two-component developer is in a tilted state. The developing device having stirring members for conveying and stirring a developer and a developer holder, comprises a developer replenishing tank for replenishing the developer to a developer tank and a trickle discharging mechanism, wherein the conveying passages thereof include an upper conveying passage, a lower conveying passage, a first communicating passage for connecting the downstream side of the upper conveying passage to the upstream side of the lower conveying passage, and a second communicating passage for connecting the downstream side of the lower conveying passage to the upstream side of the upper conveying passage, and also include a circulation passage through which the developer circulates using the upper conveying passage, the first communicating passage, the lower conveying passage and the second communicating passage; the discharging mechanism is disposed in the downstream end section of the upper conveying passage; the bottom face on the downstream side of the upper conveying passage is positioned above the bottom face on the upstream side of the lower conveying passage; and the first communicating passage is disposed obliquely downward with respect to the horizontal plane.

Developing device and image forming apparatus

An image forming apparatus has a plurality of developing devices each including a developing member carrying and transferring developer toward a developing region and a charging member charging developer carried by the developing member, a development bias applying device applying an AC development bias voltage to the developing member, and a charge bias applying device applying to the charging member an AC charge bias voltage having a phase synchronized with the AC development bias voltage and representing a charge bias voltage value causing an offset potential difference with respect to the AC development bias voltage in a phase on one of positive and negative sides. The charge bias voltage applied by the charge bias applying device provided for each of the developing devices has the same voltage value as the charge bias voltages applied by the charge bias applying devices of the other charge bias applying devices.

Image forming apparatus and developing method

A developing devicehas a voltage application memberwhich is in contact via a toner layer with a developing rollerthat rotates while holding the toner layer on its outer peripheral surface. To the toner layer, the voltage application memberapplies a relatively low voltage in an upstream-side contact portion with respect to a rotational direction of the developing roller, and applies a relatively high voltage in a downstream-side contact portion thereof.

Developing device having a voltage application member for applying varied voltages

An image forming apparatus includes a plurality of printing units each having an image bearing member for rotation about an axis and a process member which cooperates with the image bearing member in an image forming process; a transfer member for moving in contact with the image bearing member of each of the plurality of printing units, an image on each of the image bearing members being transferred onto the transfer member or a recording medium that is transported on the transfer member; a switch unit for switching between a contact state where the image bearing members in the plurality of printing units are in contact with the transfer member and a separate state where the image bearing member(s) in the printing unit(s) other than one of the plurality of printing units are separated from the transfer member; a memory for storing life expectancies of the image bearing member and the process member with regard to the printing unit(s) other than the one of the plurality of printing units; and a control section for controlling the switch unit based on a print job and the life expectancies stored in the memory.

Image forming apparatus

A developing device has a voltage application member which is in contact via a toner layer with a developing roller that rotates while holding the toner layer on its outer peripheral surface. A voltage that the voltage application member applies to the toner layer is switched between AC voltage and DC voltage based on humidity or drive cumulated time of the developing device.

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Toyohashi, Japan

Tomoyuki Imura