Canon Kabushiki Kaisha

Kosuke Takeuchi

Yusuke Ishida

Katsuya Nose

Fumiyoshi Saito

Toshihisa Yago

Naoki Mugita

Atsushi Matsumoto

Yasushi Takeuchi

Akihiro Noguchi

Kyosuke Takahashi

Mitsuhiro Furukawa

Hideki Fujita

Hirotoshi Tajima

Takashi Ninomiya

Ryosuke Kosone

An image forming apparatus includes an image bearing member, a developing apparatus, a driving device, an airflow space portion, a duct, and, a drawing fan. A driving-force transmission member, the driving device and the airflow space portion are disposed on a side on which a developer container faces the image bearing member. The driving-force transmission member, the driving device, the duct and the drawing fan are disposed on one end side of a developing rotary member in a rotation-axis direction of the developing rotary member. The duct is disposed underneath the developer container, formed from the side on which the developer container faces the image bearing member to a side opposite to the side on which the developer container faces the image bearing member. The drawing fan is disposed on the side opposite to the side on which the developer container faces the image bearing member.

Developer container with airflow space

An image forming apparatus includes an image carrier, an exposure device to expose the image carrier to form an electrostatic latent image on the image carrier, a conductive member, and a developing device having a rotatable developing roller and a rotatable toner supply roller. Polarity of direct-current components of biases applied during an image forming operation to the conductive member, the developing roller, and the toner supply roller are the same as a polarity of normally charged toner. An absolute value of the bias applied to the developing roller during the image forming operation is smaller than an absolute value of the bias applied to the toner supply roller during the image forming operation. The absolute value of the bias applied to the toner supply roller during the image forming operation is smaller than an absolute value of the bias applied to the conductive member during the image forming operation.

Image forming apparatus capable of returning scattered toner at a portion where a developing roller and a supply roller face each other to a circulation path during an image forming operation

In an image forming apparatus, a shortest distance at which a developer container is closest to an image bearing member and which is disposed downstream of a first magnetic pole and upstream of second magnetic pole of a magnet fixed within a developer bearing member is 2.5 mm or less, and a position at which a magnetic flux density in a normal direction of the developer bearing member is zeroed and which is disposed downstream of the first magnetic pole and upstream of the second magnetic pole in the rotation direction of the developer bearing member on the developer bearing member is positioned upstream of the position at which the developer container is closest to the image bearing member and which is disposed downstream of the first magnetic pole and upstream of the second magnetic pole.

Image forming apparatus

An image forming apparatus includes a controller to control a driving device such that a rotational speed of a supplying and feeding screw when it is rotated a predetermined number of times to supply developer to a developing device in a predetermined amount during execution of a continuous image forming job on a plurality of first recording materials is a first rotational speed, and a rotational speed of the supplying and feeding screw when it is rotated the predetermined number of times to supply the developer in the predetermined amount during execution of a continuous image forming job on a plurality of second recording materials is a second rotational speed slower than the first rotational speed. The second recording materials have a length longer than the first recording materials with respect to a sub-scan direction.

An image forming apparatus includes an image bearing member and a developing device having a first developer bearing member and a second developer bearing member, disposed with a gap therebetween. A controller executes a mode in which a first difference between an amplitude of an alternating current bias of a first developing bias applied to the first developer bearing member and an amplitude of an alternating current bias of a second developing bias applied to the second developer bearing member at a time of non-image formation is set to be large compared to a second difference between an amplitude of the alternating current bias of the first developing bias applied to the first developer bearing member and an amplitude of the alternating current bias of the second developing bias applied the second developer bearing member at a time of image formation.

Image forming apparatus having alternating current bias control

A developing unit includes a developing container, a developing sleeve, a developer regulating member, and a magnetic field generating portion. The magnetic field generating portion includes a drawing-up pole and a cut pole. In addition, in a peak-to-peak area, the magnetic field generating portion includes at least one of an Fr flat area in which Fr is substantially constant and an Fr attenuation area in which Fr attenuates toward the cut pole side from the drawing-up pole side, and is configured that F&#x3b8; is oriented toward the same direction as a direction of rotation of the developing sleeve in the entire peak-to-peak area.

Developing unit

Removal control performing both first and second control in series is performed. The first control involves rotating the plurality of developer bearing members in a state in which the developing bias is applied to the plurality of developer bearing members so that force acting on opposite-polarity particles from a normally charged toner in the direction of moving the particles from the developer bearing member toward the image bearing member. The second control involves rotating one developer bearing member at a faster circumferential velocity than the other developer bearing member in a state in which the developing bias is applied to the plurality of developer bearing members or the developing bias is turned off so that the force acting on the opposite-polarity particles from the normally charged toner in the direction of moving the particles from the developer bearing member toward the image bearing member.

Image forming apparatus configured to execute removal control

A developing device includes a developer carrying member, a first chamber, a second chamber, a first feeding member, and a second feeding member. The second feeding member includes first to third spiral portions and a disk portion. The disk portion includes a projected portion. When the disk portion is seen in an axial direction of the second feeding member, on the basis of a line connecting a rotation center of the disk portion and an upstream end portion of the third spiral portion with respect to a feeding direction of the third spiral portion, the projected portion is provided within a range from a position deviated by 90 degrees toward a downstream side with respect to a rotational direction of the disk portion to a position deviated by 30 degrees toward an upstream side with respect to the rotational direction of the disk portion.

Developing device

An image forming apparatus includes an image forming unit including a containing unit that contains a developer including toner and forms an image based on image data by using the toner, a supply unit that supplies the toner into the containing unit, a consumption amount calculation unit that calculates, based on information related to a density of an image corresponding to the image data, a consumption amount in the containing unit, a detection unit that detects a toner density of the developer in the containing unit, a correction amount calculation unit that calculates, based on the information and the toner density detected by the detection unit, a correction amount by which the consumption amount is corrected, and a controller that controls the supply unit based on the consumption amount and the correction amount calculated by the correction amount calculation unit.

Image forming apparatus supplying toner based on toner density of developer contained in containing unit and method for controlling image forming apparatus

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Abiko, Japan

Kosuke Takeuchi