Kyocera Document Solutions Inc.

Kyocera Mita Corporation

Asami Sasaki

Norio Kubo

Tamotsu Shimizu

Masashi Fujishima

Yasuhiro Tauchi

Yuji Toyota

Koji Suenami

Akira Matayoshi

Masaru Hatano

Hiroshi Yamazaki

Masaki Kadota

Minoru Wada

Yukihiro Mori

Hisashi Mukataka

Junichi Nakagawa

Eriko Takeuchi

An image forming apparatus includes an image carrying member, a charging device, an exposure device, a development device, and a development voltage power supply. The image carrying member has an amorphous silicon photosensitive layer formed on its surface. The development device includes a developer carrying member carrying two-component developer containing toner and carrier. The development voltage power supply applies to the developer carrying member a development voltage having an alternating-current voltage superposed on a direct-current voltage. When the blank part potential on the image carrying member is V0 [V], the direct-current voltage is Vdc [V], the peak-to-peak value of the alternating-current voltage Vac is Vpp [kV], and the gap between the image carrying member and the developer carrying member is Ds [mm], 10≤V0−Vdc≤90 and 1.2≤Vpp/Ds≤3.5 are fulfilled.

Image forming apparatus

An image forming apparatus includes a developer, a development device, and an image bearing member. The developer includes an initial developer containing an initial carrier and a replenishment developer containing a replenishment carrier. The initial carrier has a surface roughness Sa1 of at least 0.3 μm and no greater than 1.0 μm. A ratio Sa1/Sa2 of the surface roughness Sa1 of the initial carrier to a surface roughness Sa2 of the replenishment carrier is at least 1.2 and no greater than 3.4. The packing volume Vp calculated from equation (1)'Vp=100×Y/(Z×DS)' was at least 40% and no greater than 70%. In equation (1), Y represents an amount of the developer conveyed by a developer bearing member. Z represents an apparent density of the initial developer. DS represents a width of a space between the developer bearing member and the image bearing member.

Image forming apparatus and image formation method

A developing device includes a developer container, a developer carrier, and first and second stirring/conveying members. The developer container includes a first partition wall partitioning between the two conveying chambers longitudinally, a first communication portion for passing developer from the first to the second conveying chamber, a second communication portion for passing developer from the second to the first conveying chamber, a developer supply port for supplying developer in, a developer discharge portion for discharging excessive developer, a second partition wall arranged, adjacent to the regulating portion, downstream of the second communication portion to partition between the first conveying chamber and the regulating portion, and a shield portion connected to the two partition walls to bridge between them to shield a top part of the second communication portion. A gap is formed between an upper end part of the shield portion and the inner surface of the developer container.

Developing device and image forming apparatus therewith

A developing device includes a developer container, a developer carrier, and first and second members for stirring/conveying. The developer container includes a first partition wall between first and second chambers, a communication portion through which those chambers communicate at opposite ends of the first partition wall, a developer supply port, and a developer discharge portion. The first member stirs and conveys developer in the first chamber in a first direction. The second member stirs and conveys developer in the second chamber in a second direction and includes a regulating portion and a discharging blade. The developer container includes a second partition wall between the first chamber and the regulating portion. The gap from the upper end of the second partition wall to the inner surface of the developer container is larger than the gap thereto from the upper ends of a first helical blade and the regulating portion.

A bias condition determiner executes, in order, a first direct current voltage determination mode (first DC calibration) for determining a provisional reference direct current voltage that is a provisional reference for a direct current voltage of a developing bias applied to a developing roller, an inter-peak voltage determination mode (AC calibration) for determining a reference inter-peak voltage that is a reference for an inter-peak voltage of an alternating current voltage of the developing bias applied to the developing roller in an image forming operation, and a second direct current voltage determination mode (second DC calibration) for determining a reference direct current voltage that is a reference for the direct current voltage of the developing bias applied to the developing roller in the image forming operation.

A bias condition determiner executes a direct current voltage determination mode (DC calibration) for determining a reference direct current voltage that is a reference for a direct current voltage of a developing bias applied to a developing roller in an image forming operation and an inter-peak voltage determination mode (AC calibration) for determining a reference inter-peak voltage that is a reference for an inter-peak voltage of an alternating current voltage of the developing bias applied to the developing roller in the image forming operation. A calibration executor determines whether the inter-peak voltage determination mode needs to be executed in accordance with a value of the reference direct current voltage.

A developing device includes a developing container, first and second stirring-conveyance members, a developer carrier, a toner concentration sensor, a scraper, and a scraper attachment unit. The second stirring-conveyance member includes a rotation shaft, a first spiral blade to convey developer in an axial direction, and a second spiral blade to overlap a region where the first spiral blade is formed, which is opposite to the first spiral blade in phase, and lower than the first spiral blade in height in a radial direction. An absent region, where the second spiral blade does not exist, is formed in one pitch of the first spiral blade, the one pitch facing the toner concentration sensor. The scraper attachment unit is formed to extend, along a straight line passing through intersection points of the first and second spiral blades and parallel to the rotation shaft, into the absent region.

Developing device and image forming apparatus including same

A developing device includes a developing container, a toner carrier, and a plurality of air outlet ports. The plurality of air outlet ports are formed in such part of a wall of the developing container as faces the toner carrier, along a longitudinal direction of the developing container, the air outlet ports communicating with a duct next to the developing container. The toner carrier includes a coat layer on the outer circumferential surface thereof. The coat layer is formed by dripping the toner carrier into a resin coating liquid with one end in the longitudinal direction thereof first, the one end being a lower end of during the dipping, and then lifting the toner carrier out of the resin coating liquid. The toner carrier is arranged such that the lower end of during the dipping is disposed on an upstream side with respect to an airflow direction in the duct.

A developing device includes a housing, a developer carrier, a conveying member and a surface layer. The developer carrier carries a developer on a circumferential surface. The conveying member is rotatably arranged in a first conveying portion and conveys the developer in the first conveying direction and supplies the developer to the developer carrier. The surface layer is formed on a surface of a predetermined cylindrical base member. The surface layer is formed by an immersion method of immersing the base member in a predetermined immersion tank so that an axial direction of the base member extends along a vertical direction. A lower end side of the base member at the time of the immersion is arranged in an upstream side of the housing and an upper end side of the base member at the time of the immersion is arranged in a downstream side of the housing.

Developing device and image forming apparatus provided with same

Provided is a toner dispersing mechanism arranged between a toner storage container and a developing device, for dispersing toner replenished from the toner storage container. The toner dispersing mechanism includes a housing, a toner dispersing member, and a projecting portion formed continuously at least at a part of an inner wall surface in a longitudinal direction of the housing. The housing includes a toner filling port communicating to the toner storage container, and a toner discharge port communicating to the developing device. The toner dispersing member includes a rotary shaft rotatably supported in the housing, and a large number of dispersing protrusions made of an elastic material and formed on an outer peripheral surface of the rotary shaft. The large number of dispersing protrusions face the part and come into contact with the projecting portion.

Toner dispersing mechanism, developing device including the toner dispersing mechanism, and image forming apparatus

Provided is a developing device including: a developing container partitioned into a stirring-transport chamber, a supplying-transport chamber, and a collecting-transport chamber that are arranged substantially in parallel with one another, for storing a two-component developer; a developer carrying member for carrying the developer on a surface thereof; a supplying-transport member located within the supplying-transport chamber; a stirring-transport member located within the stirring-transport chamber; a collecting-transport member located within the collecting-transport chamber, for stirring and transporting the developer in the same direction as the supplying-transport member and at the different speed from the supplying-transport member; a first developer passage for passing the developer from the stirring-transport chamber to the supplying-transport chamber; a second developer passage for passing the developer from the supplying-transport chamber to the stirring-transport chamber; and a communication portion for passing the developer from the collecting-transport chamber to the supplying-transport chamber.

Developing device and image forming apparatus including the same

A developing device includes: a developing container partitioned into a stirring-transport chamber, a supplying-transport chamber, and a collecting-transport chamber; a developer carrying member for carrying the developer on a surface thereof; a supplying-transport member located within the supplying-transport chamber; a stirring-transport member located within the stirring-transport chamber, for stirring and transporting the developer in a reverse direction to the supplying-transport member; a collecting-transport member located within the collecting-transport chamber, for stirring and transporting the developer in the same direction as the supplying-transport member; a first developer passage for passing the developer from the stirring-transport chamber to the supplying-transport chamber; a second developer passage for passing the developer from the supplying-transport chamber to the stirring-transport chamber, in which a communication portion for passing the developer from the collecting-transport chamber to the supplying-transport chamber is provided on an upstream side of the second developer passage in terms of a developer transporting direction.

Provided is a toner dispersing mechanism, including: a housing arranged between a toner storage container and a developing device and provided with a toner filling port communicating to the toner storage container and a toner discharge port communicating to the developing device; and a dispersing member constituted by a large number of dispersing protrusions formed of an elastic material on a rotary shaft rotatably supported in the housing and on an outer peripheral surface of the rotary shaft, in which toner replenished from the toner storage container is dispersed and discharged into the developing device.

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Osaka, Japan

Asami Sasaki